Adsorbent materials and methods of adsorbing carbon dioxide

ABSTRACT

Methods of designing zeolite materials for adsorption of CO2. Zeolite materials and processes for CO2 adsorption using zeolite materials.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional Application of U.S. patent applicationSer. No. 15/351,693, filed Nov. 15, 2016, which claims the benefit ofU.S. Provisional Patent Application No. 62/337,991, filed 18 May 2016,entitled Absorbent Materials And Methods Of Absorbing Carbon Dioxide andU.S. Provisional Patent Application No. 62/255,789, filed 16 Nov. 2015,entitled Absorbent Materials And Methods Of Absorbing Carbon Dioxide,which all are incorporated by reference herein.

FIELD

The present invention relates to methods of designing zeolite materialsfor adsorption of CO₂ and processes for CO₂ adsorption.

BACKGROUND

Gas separation is important in many industries for removing undesirablecontaminants from a gas stream and for achieving a desired gascomposition. For example, natural gas from many gas fields can containsignificant levels of H₂O, SO₂, H₂S, CO₂, N₂, mercaptans, and/or heavyhydrocarbons that have to be removed to various degrees before the gascan be transported to market. It is preferred that as much of the acidgases H₂S and CO₂ be removed from natural gas as possible to leavemethane as the recovered component. Natural gas containing a highconcentration of CO₂ should not be directly introduced into pipelinesbecause it may be corrosive to the pipelines in the presence of water.Furthermore, small increases in recovery of methane can result insignificant improvements in process economics and also serve to preventunwanted resource loss. It is desirable to recover more than 80 vol %,particularly more than 90 vol %, of the methane when detrimentalimpurities are removed.

Additionally, synthesis gas (syngas) typically requires removal andseparation of various components before it can be used in fuel, chemicaland power applications because all of these applications have aspecification of the exact composition of the syngas required for theprocess. As produced, syngas can contain at least CO and H₂. Othermolecular components in syngas can be CH₄, CO₂, H₂S, H₂O, N₂, andcombinations thereof. Minority (or trace) components in the gas caninclude hydrocarbons, NH₃, NON, and the like, and combinations thereof.In almost all applications, most of the H₂S should typically be removedfrom the syngas before it can be used, and, in many applications, it canbe desirable to remove much of the CO₂.

Adsorptive gas separation techniques are common in various industriesusing solid sorbent materials such as activated charcoal or a poroussolid oxide such as alumina, silica-alumina, silica, or a crystallinezeolite. The selection of suitable zeolite materials is critical for CO₂capture and separation. However, a significant challenge exists inarriving at suitable materials because of the large diversity of zeolitecompositions. For example, there are approximately 220 zeolitetopologies recognized by the International Zeolite Society, which mayhave varying Si/Al ratios as well as varying cation concentrationsresulting in numerous possible zeolite materials. Thus, there is notonly a need for zeolite materials with improved adsorption capacity fora gas contaminant, such as CO₂, which can be used in various gasseparation processes but also a need for improved methods foridentifying suitable zeolite materials for CO₂ adsorption.

SUMMARY

Thus, in one aspect, embodiments of the invention provide a pressureswing adsorption process for separating CO₂ from a feed gas mixture,wherein the process comprises a) subjecting the feed gas mixturecomprising CO₂ to an adsorption step by introducing the feed gas mixtureinto a feed input end of an adsorbent bed, wherein the adsorbent bedcomprises: a feed input end and a product output end; and an adsorbentmaterial selective for adsorbing CO₂, wherein the adsorbent materialcomprises one or more of the following: (i) a zeolite having a Si/Alratio above about 100 and a framework structure selected from the groupconsisting of AFT, AFX, DAC, EMT, EUO, IMF, ITH, ITT, KFI, LAU, MFS,MRE, MTT, MWW, NES, PAU, RRO, SFF, STF, STI, SZR, TER, TON, TSC, TUN,VFI, and a combination thereof; or (ii) a zeolite with a frameworkstructure selected from the group consisting of CAS, EMT, FAU, HEU, IRR,IRY, ITT, LTA, RWY, TSC and VFI, and a combination thereof, having: (a)a Si/Al ratio of about 5 to about 85; and (b) a potassium cationconcentration of about 5% to about 100%; wherein the adsorbent bed isoperated at a first pressure and at a first temperature wherein at leasta portion of the CO₂ in the feed gas mixture is adsorbed by theadsorbent bed and wherein a gaseous product depleted in CO₂ exits theproduct output end of the adsorbent bed; b) stopping the introduction ofthe feed gas mixture to the adsorbent bed before breakthrough of CO₂from the product output end of the adsorbent bed; c) reducing thepressure in the adsorption bed to a second pressure resulting indesorption of at least a portion of CO₂ from the adsorbent bed; and d)recovering at least a portion of CO₂ from the adsorbent bed.

In still another aspect, embodiments of the invention provide a pressureswing adsorption process for separating CO₂ from a feed gas mixture,wherein the process comprises: a) subjecting the feed gas mixturecomprising CO₂ to an adsorption step by introducing the feed gas mixtureinto a feed input end of an adsorbent bed, wherein the adsorbent bedcomprises: a feed input end and a product output end; and an adsorbentmaterial selective for adsorbing CO₂, wherein the adsorbent materialcomprises a zeolite having a Si/Al ratio of between about 5 and about 45and with a framework structure selected from the group consisting ofCHA, FAU, FER, LTA, MFI, RHO, UFI, and a combination thereof; whereinthe adsorbent bed is operated at a first pressure and at a firsttemperature wherein at least a portion of the CO₂ in the feed gasmixture is adsorbed by the adsorbent bed and wherein a gaseous productdepleted in CO₂ exits the product output end of the adsorbent bed; b)stopping the introduction of the feed gas mixture to the adsorbent bedbefore breakthrough of CO₂ from the product output end of the adsorbentbed; c) reducing the pressure in the adsorption bed to a second pressureresulting in desorption of at least a portion of CO₂ from the adsorbentbed; and d) recovering at least a portion of CO₂ from the adsorbent bed.

In still another aspect, embodiments of the invention provide an apressure temperature swing adsorption process for separating a CO₂ froma feed gas mixture, wherein the process comprises: a) subjecting thefeed gas mixture comprising CO₂ to an adsorption step by introducing thefeed gas mixture into a feed input end of an adsorbent bed, wherein theadsorbent bed comprises: a feed input end and a product output end; andan adsorbent material selective for adsorbing CO₂, wherein the adsorbentmaterial comprises one or more of the following: (i) a zeolite having aSi/Al ratio above about 100 and a framework structure selected from thegroup consisting of AFT, AFX, CAS, DAC, HEU, IMF, ITH, KFI, LAU, MFS,MTT, PAU, RRO, SFF, STF, SXR, TER, TON, TUN, and a combination thereof;or a zeolite with a framework structure selected from the groupconsisting of AFT, AFX, CHA, EMT, EUO, FAU, IRR, IRY, ITT, KFI, LTA,MRE, MWW, NES, PAU, RHO, RWY, SFF, STI, TSC, UFI, VFI, and a combinationthereof, having: (a) a Si/Al ratio of about 3 to about 100; and (b) apotassium cation concentration of about 1% to about 100%; wherein theadsorbent bed is operated at a first pressure and at a first temperaturewherein at least a portion of the CO₂ in the feed gas mixture isadsorbed by the adsorbent bed and wherein a gaseous product depleted inCO₂ exits the product output end of the adsorbent bed; b) stopping theintroduction of the feed gas mixture to the adsorbent bed beforebreakthrough of CO₂ from the product output end of the adsorbent bed; c)heating the adsorbent bed to a second temperature higher than the firsttemperature, resulting in desorption of at least a portion of CO₂ fromthe adsorbent bed and recovering at least a first portion of CO₂; and d)reducing the pressure of the adsorbent bed to a second pressure lowerthan the first pressure and recovering a second portion of CO₂.

In still another aspect, embodiments of the invention provide a vacuumswing adsorption process for separating CO₂ from a feed gas mixture,wherein the process comprises: a) subjecting the feed gas mixturecomprising CO₂ to an adsorption step by introducing the feed gas mixtureinto a feed input end of an adsorbent bed, wherein the adsorbent bedcomprises: a feed input end and a product output end; and an adsorbentmaterial selective for adsorbing CO₂, wherein the adsorbent materialcomprises one or more of the following; (i) a zeolite having a Si/Alratio above about 100 and a framework structure selected from the groupconsisting of CAS, DAC, HEU, LAU, MTT, RRO, TON, and a combinationthereof; or (ii) a zeolite with a framework structure selected from thegroup consisting of AFT, AFX, EMT, EUO, IMF, IRR, IRY, ITH, ITT, KFI,MFS, MRE, MWW, NES, PAU, RWY, SFF, STF, STI, SZR, TER, TSC, TUN, VFI,and a combination thereof, having: (a) a Si/Al ratio of about 1 to about100; and (b) a potassium cation concentration of about 0% to about 100%;wherein the adsorbent bed is operated at a first pressure and at a firsttemperature wherein at least a portion of the CO₂ in the feed gasmixture is adsorbed by the adsorbent bed and wherein a gaseous productdepleted in CO₂ exits the product output end of the adsorbent bed; b)stopping the introduction of the feed gas mixture to the adsorbent bedbefore breakthrough of CO₂ from the product output end of the adsorbentbed; c) passing a purge gas, substantially free of CO₂, through theadsorbent bed thereby resulting in a reduction in the pressure in theadsorption bed to a second pressure and in desorption of at least aportion of CO₂ from the adsorbent bed; and d) recovering at least aportion of CO₂ from the adsorbent bed.

In still another aspect, embodiments of the invention provide a vacuumswing adsorption process for separating CO₂ from a feed gas mixture,wherein the process comprises: a) subjecting the feed gas mixturecomprising CO₂ to an adsorption step by introducing the feed gas mixtureinto a feed input end of an adsorbent bed, wherein the adsorbent bedcomprises: a feed input end and a product output end; and an adsorbentmaterial selective for adsorbing CO₂, wherein the adsorbent materialcomprises a zeolite with a framework structure selected from the groupconsisting of CHA, FAU, FER, LTA, MFI, RHO, UFI and a combinationthereof, having (a) a Si/Al ratio of about 3 to about 30; and (b) apotassium cation concentration of about 40% to about 100%; wherein theadsorbent bed is operated at a first pressure and at a first temperaturewherein at least a portion of the CO₂ in the feed gas mixture isadsorbed by the adsorbent bed and wherein a gaseous product depleted inCO₂ exits the product output end of the adsorbent bed; b) stopping theintroduction of the feed gas mixture to the adsorbent bed beforebreakthrough of CO₂ from the product output end of the adsorbent bed; c)passing a purge gas, substantially free of CO₂, through the adsorbentbed thereby resulting in a reduction in the pressure in the adsorptionbed to a second pressure and in desorption of at least a portion of CO₂from the adsorbent bed; and d) recovering at least a portion of CO₂ fromthe adsorbent bed.

In still another aspect, embodiments of the invention provide a vacuumtemperature swing adsorption process for separating a CO₂ from a feedgas mixture, wherein the process comprises: a) subjecting the feed gasmixture comprising CO₂ to an adsorption step by introducing the feed gasmixture into a feed input end of an adsorbent bed, wherein the adsorbentbed comprises: a feed input end and a product output end; and anadsorbent material selective for adsorbing CO₂, wherein the adsorbentmaterial comprises one or more of the following: (i) a zeolite having aSi/Al ratio above about 100 with a CAS framework structure; or (ii) azeolite with a framework structure selected from the group consisting ofAFT, AFX, CAS, DAC, EMT, EUO, HEU, IMF, IRR, IRY, ITH, ITT, KFI, LAU,MFS, MRE, MTT, MWW, NES, PAU, RRO, RWY, SFF, STF, STI, SZR, TER, TON,TSC, TUN, VFI, and a combination thereof, having: (a) a Si/Al ratio ofabout 1 to about 100; and (b) a potassium cation concentration of about0% to about 100%; wherein the adsorbent bed is operated at a firstpressure and at a first temperature wherein at least a portion of theCO₂ in the feed gas mixture is adsorbed by the adsorbent bed and whereina gaseous product depleted in CO₂ exits the product output end of theadsorbent bed; b) stopping the introduction of the feed gas mixture tothe adsorbent bed before breakthrough of CO₂ from the product output endof the adsorbent bed; c) simultaneously heating the adsorbent bed to asecond temperature higher than the first temperature and passing a purgegas, substantially free of CO₂, through the adsorbent bed therebyresulting in a reduction in the pressure in the adsorption bed to asecond pressure, resulting in desorption of at least a portion of CO₂from the adsorbent bed and recovering at least a portion of CO₂.

In still another aspect, embodiments of the invention provide a vacuumtemperature swing adsorption process for separating a CO₂ from a feedgas mixture, wherein the process comprises: a) subjecting the feed gasmixture comprising CO₂ to an adsorption step by introducing the feed gasmixture into a feed input end of an adsorbent bed, wherein the adsorbentbed comprises: a feed input end and a product output end; and anadsorbent material selective for adsorbing CO₂, wherein the adsorbentmaterial comprises one or more of the following: (i) a zeolite with aframework structure selected from the group consisting of CHA, FAU, FER,MFI, RHO, UFI and a combination thereof, having: (a) a Si/Al ratio ofabout 1 to about 20; and (b) a potassium cation concentration of about0% to about 40%; or (ii) a zeolite with a LTA framework structurehaving: (a) a Si/Al ratio of about 1 to about 20; and (b) a potassiumcation concentration of about 5% to about 40%; wherein the adsorbent bedis operated at a first pressure and at a first temperature wherein atleast a portion of the CO₂ in the feed gas mixture is adsorbed by theadsorbent bed and wherein a gaseous product depleted in CO₂ exits theproduct output end of the adsorbent bed; b) stopping the introduction ofthe feed gas mixture to the adsorbent bed before breakthrough of CO₂from the product output end of the adsorbent bed; and c) simultaneouslyheating the adsorbent bed to a second temperature higher than the firsttemperature and passing a purge gas, substantially free of CO₂, throughthe adsorbent bed thereby resulting in a reduction in the pressure inthe adsorption bed to a second pressure, resulting in desorption of atleast a portion of CO₂ from the adsorbent bed and recovering at least aportion of CO₂.

In still another aspect, embodiments of the invention provide atemperature swing adsorption process for separating CO₂ from a feed gasmixture, wherein the process comprises: a) subjecting the feed gasmixture comprising CO₂ to an adsorption step by introducing the feed gasmixture into a feed input end of an adsorbent bed, wherein the adsorbentbed comprises: a feed input end and a product output end; and anadsorbent material selective for adsorbing CO₂, wherein the adsorbentmaterial comprises a zeolite with a framework structure selected fromthe group consisting of AFT AFX, CAS, EMT, IRR, IRY, ITT, KFI, MWW, PAU,RWY, SFF, STF, TSC, UFI, VFI, and a combination thereof, having: (a) aSi/Al ratio of about 1 to about 20; and (b) a potassium cationconcentration of about 0% to about 50%; wherein the adsorbent bed isoperated at a first pressure and at a first temperature wherein at leasta portion of the CO₂ in the feed gas mixture is adsorbed by theadsorbent bed and wherein a gaseous product depleted in CO₂ exits theproduct output end of the adsorbent bed; b) stopping the introduction ofthe feed gas mixture to the adsorbent bed before breakthrough of CO₂from the product output end of the adsorbent bed; c) heating adsorbentbed to a second temperature higher than the first temperature, resultingin desorption of at least a portion of CO₂ from the adsorbent bed andrecovering at least a portion of CO₂ from the adsorbent bed.

In still another aspect, embodiments of the invention provide atemperature swing adsorption process for separating CO₂ from a feed gasmixture, wherein the process comprises: a) subjecting the feed gasmixture comprising CO₂ to an adsorption step by introducing the feed gasmixture into a feed input end of an adsorbent bed, wherein the adsorbentbed comprises: a feed input end and a product output end; and anadsorbent material selective for adsorbing CO₂, wherein the adsorbentmaterial comprises one or more of the following: (i) a zeolite with aframework structure selected from the group consisting of CHA, FAU, RHO,and a combination thereof, having: (a) a Si/Al ratio of about 1 to about20; and (b) a potassium cation concentration of about 0% to about 40%;or (ii) a zeolite with a LTA framework structure having: (a) a Si/Alratio of about 1 to about 20; and (b) a potassium cation concentrationof about 5% to about 40%; wherein the adsorbent bed is operated at afirst pressure and at a first temperature wherein at least a portion ofthe CO₂ in the feed gas mixture is adsorbed by the adsorbent bed andwherein a gaseous product depleted in CO₂ exits the product output endof the adsorbent bed; b) stopping the introduction of the feed gasmixture to the adsorbent bed before breakthrough of CO₂ from the productoutput end of the adsorbent bed; c) heating adsorbent bed to a secondtemperature higher than the first temperature, resulting in desorptionof at least a portion of CO₂ from the adsorbent bed and recovering atleast a portion of CO₂ from the adsorbent bed.

Other embodiments, including particular aspects of the embodimentssummarized above, will be evident from the detailed description thatfollows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 a-1 d illustrate contour plots of CO₂ working capacity (mol/kg)as a function of Si/Al ratio and K/(K+Na) % (potassium cationconcentration) for MWW structures in (a) PSA1, (b) VSA, (c) PTSA1, and(d) VTSA1 processes.

FIG. 2 illustrates a relationship between the working capacity and theaccessible pore volume of adsorbents for a pressure swing adsorption(PSA) process.

FIG. 3 illustrates average heats of adsorption (Q_(st)) at adsorptionand desorption conditions for the optimal composition of each topologyfor the PSA process. The dashed line indicates the mean value of theaverage Q_(st) for all optimal compositions.

FIGS. 4(a)-(f) illustrate comparison of simulated and experimentaladsorption properties of CO₂ in K-exchanged and K/Na-exchanged zeolitesas follows: (a) isotherms and (b) isosteric heats of adsorption in K-CHA(Si/Al=12), (c) isotherms and (d) isosteric heats of adsorption inK-MCM-22 (Si/Al=15), (e) isotherms in KX (Si/Al=1.23) and KY(Si/Al=2.37) at 298 K, and (0 isotherms in K/Na-LTA (Si/Al=1, 17.4% K).The experimental data are from Pham et al. (Pham, T. D.; Liu, Q. L.;Lobo, R. F. Langmuir 2013, 29, 832), Zukal et al. (Zukal, A.; Pawlesa,J.; Cejke, J. Adsorption 2009, 15, 264), Walton et al. (Walton, K. S.;Abney, M. B.; LeVan, M. D. Micropor Mesopor Mat 2006, 91, 78), and Liuet al. (Liu, Q. L.; Mace, A.; Bacsik, Z.; Sun, J. L.; Laaksonen, A.;Hedin, N. Chem Commun 2010, 46, 4502). Lines are drawn to guide the eye.

FIG. 5 illustrates a CO₂ adsorption isotherm for SSZ-35 (circles)compared to the simulated CO₂ adsorption (open squares).

FIG. 6 illustrates CO₂ adsorption isotherms at different temperatures(open symbols) for SSZ-13 (circles) compared to the simulated CO₂adsorption isotherms (points).

FIG. 7 illustrates a CO₂ adsorption isotherm for SSZ-16 (points)compared to the simulated CO₂ adsorption (lines) at 28° C. and 120° C.

DETAILED DESCRIPTION

In various aspects of the invention, adsorbent materials, adsorbentcontactors and gas separation processes using the adsorbent materialsare provided.

I. Definitions

To facilitate an understanding of the present invention, a number ofterms and phrases are defined below.

As used in the present disclosure and claims, the singular forms “a,”“an,” and “the” include plural forms unless the context clearly dictatesotherwise.

Wherever embodiments are described herein with the language“comprising,” otherwise analogous embodiments described in terms of“consisting of” and/or “consisting essentially of” are also provided.

The term “and/or” as used in a phrase such as “A and/or B” herein isintended to include “A and B”, “A or B”, “A”, and “B”.

As used herein, the term “adsorption” includes physisorption,chemisorption, and condensation onto a solid support, adsorption onto asolid supported liquid, chemisorption onto a solid supported liquid andcombinations thereof.

As used herein, the term “breakthrough” refers to the point where theproduct gas leaving the adsorbent bed exceeds the target specificationof the contaminant component. At the breakthrough point, the adsorbentbed can be considered “spent”, such that any significant furtheroperation through the spent adsorption bed alone will result inoff-specification product gas. As used herein, the “breakthrough” cangenerally coincide with the “adsorption front”, i.e., at the timebreakthrough is detected at the outlet of the adsorbent bed, theadsorption front is generally located at the end of the adsorption bed.

As used herein, the term “selectivity” refers to a binary (pairwise)comparison of the molar concentration of components in the feed streamand the total number of moles of these components adsorbed by theparticular adsorbent during the adsorption step of the process cycleunder the specific system operating conditions and feedstreamcomposition. For a feed containing component A, component B, as well asadditional components, an adsorbent that has a greater “selectivity” forcomponent A than component B will have at the end of the adsorption stepof the swing adsorption process cycle a ratio:

U_(A)=(total moles of A in the adsorbent)/(molar concentration of A inthe feed) that is greater than the ratio:

U_(B)=(total moles of B in the adsorbent)/(molar concentration of B inthe feed)

Where U_(A) is the “Adsorption Uptake of component A” and U_(B) is the“Adsorption Uptake of component B”.

Therefore for an adsorbent having a selectivity for component A overcomponent B that is greater than one:Selectivity=U _(A) /U _(B) (where U _(A) >U _(B)).

As used herein, the term “kinetic selectivity” refers to the ratio ofsingle component diffusion coefficients, D (in m²/sec), for twodifferent species. These single component diffusion coefficients arealso known as the Stefan-Maxwell transport diffusion coefficients thatare measured for a given adsorbent for a given pure gas component.Therefore, for example, the kinetic selectivity for a particularadsorbent for component A with respect to component B would be equal toDA/DB. The single component diffusion coefficients for a material can bedetermined by tests well known in the adsorptive materials art. Thepreferred way to measure the kinetic diffusion coefficient is with afrequency response technique described by Reyes et al. in “FrequencyModulation Methods for Diffusion and Adsorption Measurements in PorousSolids”, J. Phys. Chem. B. 101, pages 614-622, 1997. In a kineticallycontrolled separation it is preferred that kinetic selectivity (i.e.,DA/DB) of the selected adsorbent for the first component (e.g.,Component A) with respect to the second component (e.g., Component B) begreater than 5, greater than 20, and particularly greater than 50.

As used herein, the term “equilibrium selectivity” is defined in termsof the slope of the single component uptake into the adsorbent (inμmole/g) vs. pressure (in torr) in the linear portion, or “Henry'sregime”, of the uptake isotherm for a given adsorbent for a given purecomponent. The slope of this line is called herein the Henrys constantor “equilibrium uptake slope”, or “H”. The “equilibrium selectivity” isdefined in terms of a binary (or pairwise) comparison of the Henrysconstants of different components in the feed for a particularadsorbent. Therefore, for example, the equilibrium selectivity for aparticular adsorbent for component A with respect to component B wouldbe HA/HB. It is preferred that in an equilibrium controlled separationthe equilibrium selectivity (i.e., HA/HB) of the selected adsorbent forthe first component (e.g., Component A) with respect to the secondcomponent (e.g., Component B) be greater than 5, greater than 20, andparticularly greater than 50.

As used herein, the term “Si/Al ratio” is defined as the molar ratio ofsilica to alumina of a zeolitic structure.

II. Methods of Designing Zeolite Materials for CO₂ Adsorption

In a first embodiment, a method of designing a zeolite material for CO₂adsorption is provided. To describe adsorption of CO₂ molecules inzeolites, the following three interactions need to be studied: 1)CO₂-zeolite; 2) cation-framework structure; and 3) CO₂—CO₂. The EPM2model (see Harris and Young, J. Phys. Chem., 1995, 99 12021) may be usedto represent the CO₂—CO₂ interaction because the phase behavior of pureCO₂ is correctly captured. For the CO₂-zeolite and the cation-frameworkstructure interactions, a first-principles-based force fields forcrystalline porous materials approach may be used. Specifically, a fullyperiodic framework to represent adsorbent structure may be used andquantum chemistry calculations for numerous adsorption configurationsrandomly scattered throughout the whole framework may be made. Thisapproach may be used for adsorption of CO₂ in siliceous zeolites andalso for cation exchanged zeolites (e.g., potassium cation, sodiumcation, etc.). See Fang et al., J. Phys. Chem. C, 2012, 116, 10692; Fanget al., Phys Chem. Chem. Phys., 2013, 15, 12882. The developed forcefields may accurately predict experimental adsorption properties andshow transferability across different zeolite topologies. An example offirst-principles-derived force field parameters are shown in Tables 1, 2and 3 below.

TABLE 1 First-Principls-Derived Force Field Parameters For CO₂ InK/Na-Exchanged Zeolites-Shown Are Lennard-Jones Potential Parameters AndPartial Charges For Coulombic Interactions CCFF Cross Species ε/k_(b)(K) σ(Å) Charge (e) Si—C 49.75 3.620 Si (2.21) Si—O 38.90 3.494 O_(z)^(Si) (−1.105) O_(z)—C 29.12 3.193 O_(z) ^(Al) (1.32) O_(z)—O 23.433.067 Al (2.08) Al—C 32.21 3.366 K (0.99) Al—O 25.32 3.246 Na (0.99) K—C60.60 3.232 H (0.51) K—O 48.19 3.111 Na—C 66.78 2.827 Na—O 54.76 2.707H—O 225.46 1.969 H—C 270.70 2.061

TABLE 2 Buckingham Parameters For K-And Na-Framework Interactions CrossSpecies A (eV) B (Å) C (eV) K—O_(z) 5258.3 0.2916 193.7 Na—O_(z) 3261.60.2597  45.4

TABLE 3 Morse Potential Parameters For H-Framework Interactions CrossSpecies p₀/k_(B)(K) p₁ p₂ (Å) H-O_(z) ^(Si) 16113.4 6.3457 1.1239H-O_(z) ^(Al) 16113.4 6.3457 1.1239

Here Morse potential is defined as (Demiralp et al, Phys. Rev. Lett.1999, 82, 1708):U=p ₀[e ^(p) ¹ ^(*(1−r/p) ² ⁾−2e ^((p) ¹ ^(/2)*(1−r/p) ² ⁾]

During molecular simulations of adsorption isotherms, framework atomsmay be fixed and extra-framework cations may be allowed to move (seee.g. Fang et al., Phys Chem. Chem. Phys., 2013, 15, 12882). Thepositions of extra-framework cations can have a significant impact onthe adsorption properties. For most cationic zeolites, however, theexperimental information for cation locations is not available. To getmore reliable cation distributions for each material, pre-equilibrationsimulations prior to the adsorption of CO₂ may be performed. Paralleltempering (also known as canonical replica-exchange Monte Carlo) may beused in these simulations. For each cationic material, replicas (e.g.,9) may be included in simulations at temperatures, such as 300K, 390K,507K, 659K, 857K, 1114K, 1448K, 1882K and 2447K, respectively. Thelowest temperature may be room temperature, and the highest temperatureshould be high enough so as to ensure that no replicas become trapped inlocal energy minima. Reasonable degree of overlap between the potentialenergy distributions of neighboring state points was found.

Adsorption isotherms of CO₂ in zeolites may be predicted computationallyusing standard Grand Canonical Monte Carlo (GCMC) methods. The chemicalpotential may be determined from the fugacity, and the fugacitycoefficients may be computed using the Peng-Robinson equation of state(Peng and Robinson Ind. Eng. Chem. Fundam. 1976, 15, 59). Isostericheats of adsorption, Q_(st), defined as the difference in the partialmolar enthalpy of the adsorption between the gas phase and the adsorbedphase, may be determined. Some topologies, for example, FAU and LTA,include regions such as sodalite cages that are inaccessible for CO₂molecules. These regions may be blocked in the simulations to avoidspurious adsorption of CO₂ in these regions.

Accessible pore volume, which is defined as the percentage of the porevolume to the total volume of the zeolite, may be computed from Widomparticle insertion using Helium. For the calculations of pore volumes,the Clay Force Field (CLAYFF) may be used for the atoms of the zeoliteand force field parameters from the previous work may be used for He—Heinteractions (See Cygan et al., J. Phys. Chem. B, 2004, 108, 1255; Taluet al. Colloids and Surfaces a-Physicochemical and Engineering Aspects,2001, 187, 83). Lorentz-Berthelot mixing rules may be applied for thecross species interactions.

Prototypical processes may be defined for CO₂ capture. For example, thefollowing processes such as in Table 3 may be modeled. It understoodthat CO₂ adsorption processes are not limited to processes considered inTable 4.

TABLE 4 Processes Considered Adsorption Desorption Processes T (K) P(bar) T (K) P (bar) PSA1 300 5 300 1 PSA2 300 20 300 1 PSA3 300 0.066300 0.0026 PSA4 233 0.066 233 0.0026 PTSA1 300 5 373 1 PTSA2 300 20 3731 VSA 300 1 300 0.1 VTSA1 300 1 373 0.1 VTSA2 300 1 473 0.2 VTSA3 300 5473 0.2 TSA 300 1 473 1

The choice of adsorption and desorption conditions may vary and be basedon previous research and industrial relevance. The conditions in Table 3are representative of only several possible set of conditions. Detailedprocess modeling of gas capture may require a description ofmulti-component adsorption of the gas mixtures of interest. As a firststep, it may be sufficient to focus simply on the capacity a materialhas for the primary component of interest (e.g., CO₂). For example,zeolites as potential adsorbents for CO₂ may be considered based onsingle-component adsorption of CO₂.

For each process the working capacity (ΔN), which is defined as thedifference between the adsorbed amounts of CO₂ at the adsorption(N_(ads)) and desorption (N_(des)) conditions, may be used to evaluateadsorption performance of the materials. Thus, via molecular simulationsusing the first-principles-derived force fields, the relationshipbetween CO₂ working capacity and Si/Al ratio and cation concentration(e.g., sodium cation, potassium cation) may be determined for eachzeolite framework structure at each defined process condition. For eachframework structure, the optimal composition may be determined for eachspecified process. The optimal compositions for selected processes inTable 4 are shown below in Table 5.

TABLE 5 Examples Of Working Capacity Of The Optimal Compositions ForSelected Zeolite Topologies In The Four CO₂ Adsorption Processes PSA1VSA PTSA1 VTSA1 ΔN ΔN ΔN ΔN Zeolite (mmol/cc) Zeolite (mmol/ cc) Zeolite(mmol/cc) Zeolite (mmol/cc) RWY_5_100 6.49 RWY_3_17 5.34 RWY_3_17 11.17IRY_2_0 8.78 IRY_10_100 4.98 IRY_3_83 4.48 IRY_3_0 8.68 IRR_2_0 7.82FAU_50_67 4.40 FAU_5_100 4.28 IRR_5_50 7.76 FAU_2_33 7.51 TSC_50_83 4.36IRR_3_100 3.79 FAU_5_83 7.12 EMT_2_ 0 7.26 IRR_10_100 4.25 EMT_ 5_833.78 TSC_10_17 6.87 RWY_3_17 7.14 EMT_50_100 4.12 VFI_1_0 3.52 EMT_5_336.74 TSC_1_0 6.60 LTA_50_67 3.75 RRO_Si 3.43 VFI_1_0 6.38 LTA_1_ 0 5.93VFI_10_100 3.46 DAC_ Si 3.39 LTA_10_33 5.87 VFI_2_0 5.31 SFF_Si 3.14LTA_5_50 3.30 STF_Si 5.50 STF_5_0 5.24 STF_Si 3.13 TSC_ 5_0 3.27 DAC_Si5.42 SFF_3_0 5.05 MWW_Si 2.91 STF_50_100 3.13 RRO_Si 5.06 MWW_2_33 4.87ITH_Si 2.50 HEU_Si 2.84 SFF_50_100 4.94 STI_2_0 4.82 NES_Si 2.39MWW_10_100 2.72 MWW_25_100 4.90 DAC_50_17 4.75 TUN_Si 2.32 SFF_25_672.69 ITH_Si 4.22 RRO_10_83 4.57 TER_Si 2.24 TER_50_100 2.31 TER_Si 4.20NES_2_0 4.47 FER_Si 2.23 STI_10_83 2.29 STI_10_100 4.18 HEU_25_17 4.11MFS_Si 2.19 MFS_25_100 2.25 NES_50_100 4.15 MFS_10_17 4.04 IMF_Si 2.09TUN_50_100 2.23 TUN_Si 4.10 FER_10_33 3.79 STI_Si 2.08 NES_10_67 2.22HEU_Si 4.07 SZR_5_67 3.77 SZR_Si 1.95 FER_50_100 2.18 FER_Si 4.05EUO_3_0 3.77 MFI_Si 1.92 ITH_25_100 2.17 MFS_Si 3.97 ITH_10_17 3.74EUO_Si 1.88 LAU_Si 2.15 LAU_Si 3.81 TER_10_17 3.66 DAC_Si 1.81MFI_50_100 2.13 MFI_Si 3.79 TUN_10_67 3.60 LAU_Si 1.81 SZR_50_83 2.05SZR_Si 3.78 LAU_100 3.44 RRO_Si 1.59 EUO_25_100 1.98 IMF_Si 3.78MFI_10_33 3.34 TON_Si 1.48 IMF_50_100 1.96 EUO_25_100 3.58 IMF_100 3.28MTT_Si 1.41 TON_Si 1.95 TON_Si 3.32 MTT_10_83 2.60 HEU_50_100 1.21MTT_Si 1.59 MTT_Si 2.89 TON_25_0 2.46 ^(a)To describe the materials, weuse ZEO_A_B to represent cationic zeolites, where ZEO indicates thetopology type, A the Si/Al ratio, and B the percentage concentration ofK cations. For siliceous zeolites, we use ZEO_Si.

The zeolite materials described herein may be represented by thefollowing formula ZEO_A_B, wherein “ZEO” represents the frameworkstructure, “A” represents the Si/Al ratio and “B” represents theconcentration of potassium cations. For example, MFI 10_50 represents azeolite material having an MFI framework structure, a Si/Al ratio of 10and a potassium cation concentration of 50%. MFI_Si represents a zeolitematerial having an MFI framework structure that is highly siliceous. Asused herein, “highly siliceous” refers to a zeolite material having aSi/Al ratio of ≥about 100, ≥about 150, ≥about 200, ≥about 250, ≥about300, ≥about 350, ≥about 400≥about 450, ≥about 500, ≥about 550, ≥about600, ≥about 650, ≥about 700, ≥about 750, ≥about 800, ≥about 850, ≥about900, ≥about 950, or ≥about 1000. In particular, a highly siliceouszeolite has a Si/Al ratio of above 100. Such highly siliceous zeolitesmay include a cation concentration of less than about 10%, less thanabout 5%, less than about 1%, less than about 0.1%, or about 0%.

Also, it has been found that a substantially linear relationship betweenworking capacity and accessible pore volume exists for the optimalcompositions of the framework structures for the processes studied, asshown in FIG. 2 for the PSA1 process. It was further found that theaverage Q_(st) are located within a narrow range for each process, asshown in FIG. 3 for the PSA1 process. In contrast, the heats ofadsorption at zero coverage)(Q_(st) ⁰) are located in a relativelylarger range for each process. The results indicated that suitableaverage Q_(st) are required for maximizing the working capacity of eachtopology in a specified process. Too high an average Q_(st) may lead toa large amount of residual adsorbed adsorbate at the desorptionpressure, and therefore to a reduced working capacity, whereas too lowan average Q_(st) may also result in a low working capacity. As aresult, for each topology there is an optimal average Q_(st) forobtaining the maximum working capacity.

Thus, in various aspects, a method of designing zeolites for CO₂adsorption involves identifying a target adsorption process for CO₂. Anysuitable CO₂ adsorption process known in the art may be targeted.Non-limiting examples of suitable CO₂ adsorption processes includepressure swing adsorption (PSA), temperature swing adsorption (TSA),pressure temperature swing adsorption (PTSA), vacuum swing adsorption(VSA), vacuum temperature swing adsorption (VTSA), partial pressureswing adsorption (PPSA), partial pressure temperature swing adsorption(PPTSA), and displacement desorption swing adsorption (DDSA), and anyother combinations thereof. Once the CO₂ adsorption process isidentified, zeolite framework structure may be selected. In particular,zeolite framework structures with large accessible pore volumes from0.15 and higher may be selected. Examples of suitable zeolite frameworkstructures include but are not limited to AFT, AFX, CAS, CHA, DAC, EMT,EUO, FAU, FER, HEU, IMF, IRR, IRY, ITH, ITT, KFI, LAU, LTA, MFI, MFS,MRE, MTT, MWW, NES, PAU, RHO, RRO, RWY, SFF, STF, STI, SZR, TER, TON,TSC, TUN, UFI, and VFI. A person of ordinary skill in the art knows howto make the zeolites having an aforementioned framework structure. Forexample, see the references provided in the International ZeoliteAssociation's database of zeolite structures found atwww.iza-structure.org/databases.

Following selection of a zeolite framework, the Si/Al ratio may beadjusted in order to arrive at a heat of adsorption (Q_(st)) thatresults in a high CO₂ working capacity (ΔN) for zeolite material in theidentified CO₂ adsorption process. As used herein, a “high workingcapacity” or “high ΔN” may be ≥about 1.0 mmol/cc, ≥about 2.0 mmol/cc,≥about 3.0 mmol/cc, ≥about 4.0 mmol/cc, ≥about 5.0 mmol/cc, ≥about 6.0mmol/cc, ≥about 7.0 mmol/cc, ≥about 8.0 mmol/cc, ≥about 9.0 mmol/cc,≥about 10.0 mmol/cc, ≥about 11.0 mmol/cc, ≥about 12.0 mmol/cc, ≥about13.0 mmol/cc, ≥about 14.0 mmol/cc, ≥about 15.0 mmol/cc, ≥about 16.0mmol/cc, ≥about 17.0 mmol/cc, ≥about 18.0 mmol/cc, ≥about 19.0 mmol/cc,or ≥about 20.0 mmol/cc. Examples of suitable Si/Al ratios include, butare not limited to about 1, about 2, about 3, about 5, about 9, about10, about 15, about 20, about 25, about 30, about 35, about 40, about45, about 50, about 55, about 60, about 65, about 70, about 75, about80, about 85, about 90, about 95, or about 100. Ranges expresslydisclosed include combinations of the above-enumerated values, e.g.,about 1 to about 100, about 3 to about 100, about 1 to about 75, about 1to about 20, about 1 to about 10, about 9 to about 85, about 9 to about70, about 5 to about 45, about 40 to about 60, about 3 to about 100,about 3 to about 75, about 5 to about 60, about 3 to about 60, about 3to about 30, etc.

Additionally, cations may be introduced into the zeolite material atvarying concentrations to arrive at a high CO₂ working capacity for thezeolite material. The concentration of cations is the percentage ofspecific cations to the total number of positively charged extraframework cations and protons, which are required to balance the chargein the specific zeolite framework. Examples of suitable cations include,but are not limited to potassium cations (K⁺), sodium cations (Na^(t)),lithium cations (Li^(t)), cesium cations (Cs⁺), rubidium cations (Rb⁺),silver cations (Ag⁺), calcium cations (Ca²⁺), magnesium cations (Mg²⁺),barium cations (Ba²⁺), strontium cations (Sr²⁺), copper cations (Cu²⁺),and protons (tn. For example, the zeolite material may have a cation(e.g., potassium cation, sodium cation) concentration of ≥about 0.0%,≥about 5.0%, ≥about 10.0%, ≥about 15.0%, ≥about 16.7%, ≥about 20.0%,≥about 25.0%, ≥about 30.0%, ≥about 33.4%, ≥about 35.0%, ≥about 40.0%,≥about 45.0%, ≥about 50.0%, ≥about 55.0%, ≥about 60.0%, ≥about 65.0%,≥about 66.7%, ≥about 70.0%, ≥about 75.0%, ≥about 80.0%, ≥about 83.3%,≥about 85.0%, ≥about 90.0%, ≥about 95.0%, or about 100%. Rangesexpressly disclosed include combinations of the above-enumerated values,e.g., about 0.0% to about 100%, about 1.0% to about 100%, about 5.0% toabout 100%, about 10% to about 100%, about 0.0% to about 90.0%, about0.0% to about 40.0%, about 40.0% to about 100%, about 0% to about 50%,about 5% to about 40%, etc. In particular, the Si/Al ratio may beadjusted in the zeolite material before the introduction of cations.Once the desired zeolite material is designed, experimental testing maybe undergone on the zeolite material where other factors, such as energycosts for adsorbent regeneration, adsorption kinetics, etc., may beconsidered.

III. CO₂ Adsorption Processes

In another embodiment, a CO₂ adsorption process is provided herein. TheCO₂ adsorption process comprises contacting a gas mixture containing CO₂with an adsorbent material, wherein the adsorbent material may bedesigned according to the description above.

In various aspects, the CO₂ adsorption process can be achieved by swingadsorption processes, such as pressure swing adsorption (PSA) andtemperature swing adsorption (TSA) and combinations thereof (e.g.,pressure temperature swing adsorption (PTSA)). All swing adsorptionprocesses have an adsorption step in which a feed mixture (typically inthe gas phase) is flowed over an adsorbent that preferentially adsorbs amore readily adsorbed component relative to a less readily adsorbedcomponent. A component may be more readily adsorbed because of kineticor equilibrium properties of the adsorbent material.

PSA processes rely on the fact that gases under pressure tend to beadsorbed within the pore structure of the adsorbent materials.Typically, the higher the pressure, the greater the amount of targetedgas component that will be adsorbed. When the pressure is reduced, theadsorbed targeted component is typically released, or desorbed. PSAprocesses can operate across varying pressures. For example, a PSAprocess that operates at pressures below atmospheric pressure is avacuum swing adsorption (VSA) process. PSA processes can be used toseparate gases of a gas mixture, because different gases tend to fillthe pores or free volume of the adsorbent to different extents due toeither the equilibrium or kinetic properties of the adsorbent. In manyimportant applications, to be described as “equilibrium-controlled”processes, the adsorptive selectivity is primarily based upondifferential equilibrium uptake of the first and second components. Inanother important class of applications, to be described as“kinetic-controlled” processes, the adsorptive selectivity is primarilybased upon the differential rates of uptake of the first and secondcomponents.

TSA processes also rely on the fact that gases under pressure tend to beadsorbed within the pore structure of the adsorbent materials. When thetemperature of the adsorbent is increased, the adsorbed gas is typicallyreleased, or desorbed. By cyclically swinging the temperature ofadsorbent beds, TSA processes can be used to separate gases in a mixturewhen used with an adsorbent selective for one or more of the componentsin a gas mixture. Partial pressure purge displacement (PPSA) swingadsorption processes regenerate the adsorbent with a purge. Rapid cycle(RC) swing adsorption processes complete the adsorption step of a swingadsorption process in a short amount of time. For kinetically selectiveadsorbents, it can be preferable to use a rapid cycle swing adsorptionprocess. If the cycle time becomes too long, the kinetic selectivity canbe lost. These swing adsorption protocols can be performed separately orin combinations. Examples of processes that can be used herein eitherseparately or in combination are PSA, TSA, PTSA, VSA, VTSA, PPSA, PPTSADDSA.

Additionally or alternatively, the processes of the present inventioncan comprise an adsorption step in which the preferentially adsorbedcomponents (e.g., CO₂) of the feed mixture can be adsorbed by theadsorbent material described herein as contained in an adsorbentcontactor, such as an adsorbent bed, while recovering the lesspreferentially adsorbed components at the product end of the adsorbentbed at process pressures. The adsorption step may be performed at afirst pressure such that the partial pressure of CO₂ is from about 0.5bar to about 25 bar, particularly about 3 bar to about 25 bar,particularly about 15 bar to about 25 bar, particularly about 3 bar toabout 10 bar, particularly about 0.5 bar to about 7 bar, or particularlyabout 0.5 bar to about 3 bar. Additionally or alternatively, theadsorption step of the present invention can be performed at a firsttemperature from about −20° C. to about 80° C., particularly from about0° C. to about 50° C. or particularly from 10° C. to 30° C. Additionallyor alternatively, heat of adsorption can be managed by incorporating athermal mass into the adsorption bed to mitigate the temperature riseoccurring during the adsorption step. The temperature rise from the heatof adsorption can additionally or alternately be managed in a variety ofways, such as by flowing a cooling fluid through the passages externalto the adsorbent bed (i.e., the passages that are used to heat and coolthe contactor).

Additionally or alternatively, the passages external to the adsorbentbed can be filled with a fluid that is not flowing during the adsorptionprocess. In this case, the heat capacity of the fluid can serve tomitigate the temperature rise in the adsorbent bed. Combinations of someor all of these heat management strategies can be employed. Even withthese heat management strategies, during this step, the finaltemperature of the bed can typically be slightly higher than the feedinlet temperature. Particularly, the degree of adsorption and coolingcan be managed so that the maximum temperature rise at any point withinthe contactor can be less than about 40° C., e.g., less than about 20°C., less than about 10° C., or less than about 5° C. During adsorption,the strongest-adsorbing components can tend to attach most strongly tothe adsorbent and can thus be least mobile. Such strongest-adsorbingcomponents can thus tend to occupy regions of adsorbent closest to theinlet and can generally displace weakly adsorbed components from thoseregions.

Over the period of adsorption, the adsorbates can tend to orderthemselves from strongest to weakest, moving from inlet to outlet of theadsorption channels of the contactor. In preferred embodiments, the feedgas velocity can be chosen so that a relatively sharp concentrationfront moves through the contactor, i.e., such that the concentrationgradient of adsorbate(s) extends over a relatively short distance,taking into consideration the absolute amplitude of the gradient.

The adsorption step can be stopped at a predetermined point before theadsorption front breaks through the product output end of the adsorbentbed. The adsorption front can move at least 30% of the way down the bed,e.g., at least 50% or at least 80%, before the adsorption step isstopped. Additionally or alternatively, the adsorption step can beconducted for a fixed period of time set by the feed flow rate andadsorbent capacity. Further additionally or alternatively, theadsorption step can be conducted for a time less than 600 seconds,particularly less than 120 seconds, e.g., less than 40 seconds or lessthan 10 seconds, or less than 5 seconds. In some instances, theadsorption front can be allowed to break through the output end only fora short duration (e.g., for at most a few seconds), but usually theadsorption front is not allowed to break through, which can maximizeutilization of the bed.

After the adsorption step, the feed gas channels in the contactor canoptionally be depressurized to a second pressure lower than the firstpressure. For example, the second pressure may be such that the partialpressure of CO₂ is from about 0.5 bar to about 2 bar, particularly about0.05 bar to about 0.5 bar, particularly about 0.08 bar to about 0.3 bar,or particularly about 0.09 bar to about 0.4 bar. Reduction in pressureto a second pressure may be achieved by passing a purge gas,substantially free of target gas species (e.g., CO₂) through adsorbentbed. The purge gas may comprise an inert gas, such as nitrogen.

Additionally or alternatively, the feed input end of the adsorbent bedcan be sealed with respect to the passage of a gas, and heat can beexternally applied to the adsorbent bed. By “externally heated” it ismeant that heat is not applied directly to the adsorbent bed through theflow channels through which the feed gas mixture had flowed and intowhich the target gas component will be desorbed. The heat can bedelivered to the adsorbent bed through a plurality of heating/coolingchannels in thermal communication, but not in fluid communication, withthe feed gas flow channels of the adsorbent. The adsorbent bed can beexternally heated co-currently or counter-currently along its lengthwith respect to the flow of the feed gas mixture, or in a combination ofco-current and counter-current heating steps. The flow channels thatwill carry heating and cooling fluid can be in physical contact with theadsorbent bed to enhance heat transfer. The adsorbent bed can be heatedto a second temperature higher than the first temperature used duringthe adsorption step, the second temperature at least about 10° C. higherthan the first temperature, e.g., at least about 20° C. higher, at leastabout 40° C. higher, at least about 75° C. higher, at least about 90° C.higher, at least about 100° C. higher, at least about 125° C. higher, atleast about 150° C. higher, at least about 175° C. higher or at leastabout 200° C. higher; additionally or alternatively, the secondtemperature can be from about 50° C. to about 250° C., e.g., from about150° C. to 250° C., from about 50° C. to about 150° C., from about 75°C. to about 125° C. or from about 175° C. to about 225° C.

During the heating step, the gas pressure in the channel can tend torise. To improve regeneration at the product end of the bed, during theheating step, the bed can advantageously be slowly purged with clean gasfrom the clean end (product end) of the adsorbent bed to the point ofproduct recovery. By “clean gas” it is meant that a gas is substantiallyfree of target gas components. For example, if the target gas is CO₂,then the clean gas will be a stream substantially CO₂. In oneembodiment, clean gas will contain less than 5 mol % CO₂, andparticularly less than 1 mol % of CO₂. An example of a suitable cleangas would be the product gas itself. When the current invention isutilized for the removal of CO₂ from a natural gas stream, in oneembodiment, the “clean gas” is comprised of at least one of thehydrocarbon product streams, and in another embodiment is comprised ofC₃-hydrocarbons, and in another embodiment is comprised of methane. Inother embodiments, a separate “clean gas” can be used. In one of theseembodiments, the “clean gas” is comprised of nitrogen.

The purge can be introduced at a pressure higher than the pressure inthe adsorbent bed. It can be preferred for the total number of moles ofpurge gas introduced to be less that the number of moles of moleculesadsorbed in the contactor, e.g., less than 25% or less that 10% of thenumber of moles adsorbed. By preventing the adsorption front frombreaking through, the product end of the bed can be kept substantiallyfree of the strongly-adsorbed species and can advantageously containpredominantly product species. The isotherms of the adsorbed targetcomponent can determine the partial pressure of the preferentiallyadsorbed component in equilibrium, with the new loading at the highertemperature. This partial pressure can, in some cases, be in excess of40% greater than the feed pressure, or as much as 70% higher or more.Additionally or alternatively to the recovered sensible heat, a smallamount of extra heat may be required to heat the bed to the finalpredetermined temperature. The isotherm can describe the amount ofloading (mmol of adsorbed species per gram of adsorbent) for bothchemisorption and physisorption processes.

The external heating can be conducted such that a thermal wave is usedto pass heat through the contactor, as it transitions from theadsorption step to the regeneration step, in transitioning from theregeneration to adsorption step, in at least part of the regenerationstep, and/or in at least part of the adsorption step. Similarly, it canbe preferred to utilize a thermal wave in the cooling step. A thermalwave is a relatively sharp temperature gradient, or front, that can movelinearly (i.e., approximately in a single direction within thecontactor) during at least one step in the thermal swingadsorption/desorption cycle. The speed at which the thermal front (i.e.,region with sharp temperature gradient) can move is referred to as thethermal wave velocity. The thermal wave velocity need not be constant,and the thermal wave direction need not be the same in both adsorptionand regeneration steps. For example, the wave can move co-currently,counter-currently, or cross-flow in the adsorption and/or regenerationsteps. It is also possible to design a process in which there is nosignificant thermal wave present in the adsorption step while there is asignificant thermal wave in the regeneration step. The presence of athermal wave in at least some portion of the thermal swingadsorption/regeneration cycle can enable the overall system to achieve agoal of substantially recuperating and recovering the heat required totemperature-swing the adsorbent bed. This, in turn, can improve processefficiency and/or can enable the use of high desorption temperaturesthat would not normally be considered for TSA operation.

Additionally or alternatively, the contactor is combined with theadsorbent material into a heat exchange structure in a manner that canproduce a thermal wave. In Thermal Wave Adsorption (TWA), adsorbent canbe placed in one set of heat exchanger channels, while the other set ofchannels can be used to bring heat into and/or take heat out of theadsorbent device. Fluids and/or gases flowing in the adsorbent andheating/cooling channels do not generally contact each other. The heatadding/removing channels can be designed and operated in a manner thatresults in a relatively sharp temperature wave in both the adsorbent andin the heating and cooling fluids during the heating and cooling stepsin the cycle. An example of a contactor that can produce a relativelysharp thermal wave is a contactor as described herein.

Relatively sharp thermal waves, as used herein, can be expressed interms of a standard temperature differential over a distance relative tothe length of the mass/heat transfer flow in the apparatus. With respectto the mass/heat transfer, we can define a maximum temperature, T_(max),and a minimum temperature, T_(min), as well as convenient temperaturesabout 10% above T_(min) (T₁₀) and about 10% below T_(max) (T₉₀). Thermalwaves can be said to be relatively sharp when at least the temperaturedifferential of (T₉₀-T₁₀) occurs over at most 50% (e.g., at most 40%, atmost 30%, or at most 25%) of the length of the apparatus thatparticipates in the mass/thermal transfer. Additionally oralternatively, relative sharp thermal waves can be expressed in terms ofa maximum Peclet number, Pe, defined to compare axial velocity of theheating/cooling fluid to diffusive thermal transport roughlyperpendicular to the direction of fluid flow. Pe can be defined as(U*L)/α, where U represents the velocity of the heating/cooling fluid(in m/s), L represents a characteristic distance over which heat istransported (to warm/cool the adsorbent) in a direction roughlyperpendicular to the fluid flow, and a represents the effective thermaldiffusivity of the contactor (in m²/s) over the distance L. In additionor alternately to the thermal differential over length, thermal wavescan be said to be relatively sharp when Pe is less than 10, for exampleless than 1 or less than 0.1. To minimize time for heating/cooling ofthe contactor with little or no damage to the flow channel, it can bepreferred for U to be in a range from about 0.01 m/s to about 100 m/s,e.g., from about 0.1 m/s to about 50 m/s or from about 1 m/s to about 40m/s. Additionally or alternatively, to minimize size and energyrequirements, it can be preferred for L to be less than 0.1 meter, e.g.,less than 0.01 meter or less than 0.001 meter.

Thermal waves in such contactors can be produced when the heating andcooling fluids are flowed co-current or counter-current to the directionof the feed flow in the adsorption step. In many cases, it can bepreferred not to have a significant flow of heating or cooling fluidsduring the adsorption step. A more comprehensive description of ThermalWave Adsorption (TWA) and other appropriate contactor structures can befound, e.g., in U.S. Pat. No. 7,938,886, which is incorporated herein byreference. This reference shows how to design and operate a contactor tocontrol the sharpness and nature of a thermal wave. A key operationalparameter can include the fluid velocity in the contactor. Key designparameters can include the mass of the contactor and heat capacity andthermal conductivity of materials used to form the contactor and heattransfer fluid. An additional key design objective for the contactor canbe finding one or more ways to reduce/minimize the distance over whichheat has to be transferred, which is why relatively sharp thermal wavescan be so desirable.

Additionally or alternatively, during the heating step, the volume offluid at a temperature no more than 10° C. warmer than the end of thecontactor from which it is produced can represent at least 25% (e.g., atleast 50% or at least 75%) of the volume of the fluid introduced intothe contactor for heating. Similarly, when the present invention isoperated to attain a thermal wave, it can be preferred that, during thecooling step, a cold fluid (such as pressurized water) can be flowedinto the contactor and a hot fluid near the temperature of the contactorat the end of the recovery step can flow out of the contactor. Most ofthe recovery step can generally occur after the contactor has beenheated. Thus additionally or alternatively during the cooling step, thevolume of fluid at a temperature no more than 10° C. colder than the endof the contactor from which it is produced can represent at least 25%(e.g., at least 50% or at least 75%) of the volume of the fluidintroduced into the contactor for cooling.

One way to efficiently utilize thermal waves in the apparatusesaccording to the invention can be for heat recovery. The recoveredenergy can be used to reduce the energy requirements for heating andcooling of the contactor, for a different contactor of a multitude ofcontactors needed for a continuous process, and/or for any otherpurpose. More specifically, energy contained in the hot stream exitingthe contactor during the cooling step can be utilized to reduce theenergy that must be supplied during the heating step. Similarly, thecold stream exiting the contactor during the heating step can beutilized to reduce the energy that must be supplied to cool fluid to besupplied to the contactor during the cooling step. There are many waysto recoup the energy. For example, the hot thermal fluid flowing out ofone contactor can be sent to another with trim heating in between,and/or the cold fluid flowing out of one contactor can be sent toanother with trim cooling in between. The thermal fluid flow pathbetween contactors can be determined by valves timed to route thermalfluid between contactors at appropriate points in the overall swingadsorption cycle. In embodiments where thermal fluid flows betweencontactors, it may also pass through a heat exchanger that adds orremoves heat from the flowing thermal fluid and/or pass through adevice, such as a compressor, pump, and/or blower, that pressurizes itso it can flow at the desired rate though the contactors. A heat storagemedium can be configured so that the energy from the thermal wave movingthrough one contactor can be stored. A non-limiting example is a tanksystem that separately stores hot and cold fluids, which can each be fedback into the contactor that produced it and/or to another contactor. Inmany embodiments, the flow of the thermal fluid through the contactorcan be arranged to minimize the mixing of the fluid in the direction ofthe general flow of the fluid through the contactor and to minimize theeffect of the thermal conductivity of the fluid on the sharpness of thetemperature wave.

Where energy is recovered, the recovered energy can be used to reducethe amount of sensible heat that must be supplied to heat and cool thecontactor. The sensible heat is determined by the heat capacity andtemperature rise (or fall) of the contactor. In some embodiments, atleast 60% (e.g., at least 80% or at least 95%) of the sensible heatrequired for heating the contactor is recouped, and/or at least 60%(e.g., at least 80% or at least 95%) of the sensible heat needed to coolthe contactor is recouped.

This external heating of the partially sealed adsorbent bed will resultin at least a portion of the target species being desorbed from theadsorbent bed. It can also result in an increase in pressure of theresulting target species component stream. At least a portion of thedesorbed target species component is recovered at pressures higher thanthat at the initiation of the heating step. That is, recovery of targetgas will take place toward the end of the heating step with minimum orno depressurization of the adsorbent bed. It is preferred that thepressure be a least 2 bar, particularly at least 5 bar higher than thatat the initiation of the heating step.

The pressure in the adsorbent bed is then reduced, particularly in aseries of blow-down steps in a co-current or counter-current and can beperformed with or without a purge gas stream to the final target gasrecovery pressure. Pressure reduction can occur in less than 8 steps,particularly in less than 4 steps, with target species being recoveredin each step. In one embodiment, the pressure is decreased by a factorof approximately three in each step. It is also preferred that thedepressurization be conducted counter-currently and that during thedepressurizing step a purge gas be passed counter-current (from productend to feed end) through the adsorbent bed. It is also preferred thatthe purge gas be a so-called clean gas as previously described.

In another embodiment, in any step, other than the adsorption step, theclean gas is conducted counter-currently through the adsorbent bed toensure that the end of the bed is substantially free of target species.In another embodiment, the clean gas is conducted counter-currentlythrough the adsorbent bed in at least a portion of the desorption steps.An effective rate of counter-current flowing clean gas is preferredduring these step(s) to overcome mass diffusion to ensure that theproduct end of the bed is kept substantially free of the target species.

After the target gas has been recovered, the adsorbent bed can be cooledand repressurized. One can cool the bed before repressurization. Theadsorbent bed can be cooled, particularly to a temperature that is nomore than 40° C. above the temperature of feed gas mixture, e.g., nomore than 20° C. above or no more than 10° C. above. Additionally oralternatively, the adsorbent bed can be cooled by external cooling in aco-current or counter-current manner, such that a thermal wave can passthrough the bed. In some such embodiments, the first part of theadsorbent bed can be cooled then repressurized. In certain of thoseembodiments, less than 90% of the length of adsorption bed can becooled, e.g., less than 50%. The adsorbent bed can additionally oralternatively be purged with a clean gas during cooling.

The adsorbent bed can then be repressurized, during and/or after thecooling step, e.g., using clean product gas or counter-currently withblow-down gas from another bed after a first stage of repressurization.The final pressure of the repressurization step can be substantiallyequal to the pressure of the incoming feed gas mixture.

The adsorbent be can be in the form of open flow channels, e.g.,parallel channel connectors, in which the majority of the open porevolume is attributable to microporous pore diameters, e.g., in whichless than 40%, particularly less than 20%, for example less than 15% orless than 10%, of its open pore volume can originate from pore diametersgreater than 20 angstroms (and less than about 1 micron; i.e., frommesoporous and macroporous pore diameters).

A flow channel is described herein as that portion of the contactor inwhich gas flows if a steady state pressure difference is applied betweenthe point/place at which a feed stream enters the contactor and thepoint/place a product stream leaves the contactor. By “open pore volume”herein, it is meant all of the open pore space not occupied in thevolume encompassed by the adsorbent material. The open pore volumeincludes all open spaces in the volume encompassed by the adsorbentmaterial, including but not limited to all volumes within the adsorbentmaterials themselves, including the pore volume of the structured oramorphous materials, as well as any interstitial open volumes within thestructure of the portion of the bed containing the adsorbent material.Open pore volume, as used herein, does not include spaces notaccompanied by the adsorbent material such as open volumes in the vesselfor entry, exit, or distribution of gases (such as nozzles ordistributor areas), open flow channels, and/or volumes occupied byfiller materials and/or solid heat adsorption materials. “Parallelchannel contactors” are defined herein as a subset of adsorbentcontactors comprising structured (engineered) adsorbents in whichsubstantially parallel flow channels are incorporated into the adsorbentstructure (typically the adsorbents can be incorporated onto/into thewalls of such flow channels). Non-limiting examples of geometric shapesof parallel channel contactors can include various shaped monolithshaving a plurality of substantially parallel channels extending from oneend of the monolith to the other; a plurality of tubular members,stacked layers of adsorbent sheets with and without spacers between eachsheet; multi-layered spiral rolls; spiral wound adsorbent sheets;bundles of hollow fibers; as well as bundles of substantially parallelsolid fibers; and combinations thereof. Parallel flow channels aredescribed in detail, e.g., in U.S. Patent Application Publication Nos.2008/0282892 and 2008/0282886, both of which are incorporated herein byreference. These flow channels can be formed by a variety of ways, and,in addition to the adsorbent material, the adsorbent contactor structuremay contain items such as, but not limited to, support materials, heatsink materials, void reduction components, and heating/cooling passages.

It can be desirable to operate with a multiplicity of contactor units,with several coupled in a heating/cooling operation and others involvedin adsorption (and/or desorption). In such an operation, the contactorcan be substantially cooled by a circulating heat transfer medium beforeit is switched into service for adsorption. One advantage of such anoperation can be that the thermal energy used to swing the bed isretained in the heat transfer medium. If adsorption were to proceedsimultaneously with cooling, then a substantial part of the heat in thebed could be lost to the adsorbate-free feed, and a higher heat loadcould be needed to restore the high temperature of the heat transfermedium.

In various aspects, the adsorbent material selective for adsorbing CO₂in the adsorption processes described herein may comprise a zeolite witha framework structure selected from group consisting of AFT, AFX, CAS,CHA, DAC, EMT, EUO, FAU, FER, HEU, IMF, IRR, IRY, ITH, ITT, KFI, LAU,LTA, MFI, MFS, MRE, MTT, MWW, NES, PAU, RHO, RRO, RWY, SFF, STF, STI,SZR, TER, TON, TSC, TUN, UFI and VFI. Additionally or alternatively, incombination with the aforementioned framework structures, the zeolitemay have a Si/Al ratio of ≥about 1, ≥about 2, ≥about 3, ≥about 5, ≥about9, ≥about 10, ≥about 15, ≥about 20, ≥about 25, ≥about 30, ≥about 35,≥about 40, ≥about 45, ≥about 50, ≥about 55, ≥about 60, ≥about 65, ≥about70, ≥about 75, ≥about 80, ≥about 85, ≥about 90, ≥about 95, ≥about 100,≥about 150, ≥about 200, ≥about 250, ≥about 300, ≥about 350, ≥about400≥about 450, ≥about 500, ≥about 550, ≥about 600, ≥about 650, ≥about700, ≥about 750, ≥about 800, ≥about 850, ≥about 900, ≥about 950, or≥about 1000. Additionally or alternatively, in combination with theaforementioned framework structures, the zeolite may have a Si/Al ratioof ≤about 1, ≤about 2, ≤about 3, ≤about 5, ≤about 9, ≤about 10, ≤about15, ≤about 20, ≤about 25, ≤about 30, ≤about 35, ≤about 40, ≤about 45,≤about 50, ≤about 55, ≤about 60, ≤about 65, ≤about 70, ≤about 75, ≤about80, ≤about 85, ≤about 90, ≤about 95, ≤about 100, ≤about 150, ≤about 200,≤about 250, ≤about 300, ≤about 350, ≤about 400≤about 450, ≤about 500,≤about 550, ≤about 600, ≤about 650, ≤about 700, ≤about 750, ≤about 800,≤about 850, ≤about 900, ≤about 950, or ≤about 1000. Ranges expresslydisclosed include combinations of the above-enumerated upper and lowerlimits, e.g., about 1 to about 1000, about 5 to about 100, about 10 toabout 90, about 1 to about 70, about 3 to about 85, etc.

Additionally or alternatively, in combination with the aforementionedframework structures and/or Si/Al ratios, the zeolite may have a cation(e.g., potassium cations (K⁺), sodium cations (Na⁺), lithium cations(Li⁺), cesium cations (Cs⁺), rubidium cations (Rb⁺), silver cations(Ag⁺), calcium cations (Ca²⁺), magnesium cations (Mg²⁺), barium cations(Ba²⁺), strontium cations (Sr²⁺), copper cations (Cu²⁺), and protons(H⁺)) concentration of ≥about 0.0%, ≥about 5.0%, ≥about 10.0%, ≥about15.0%, ≥about 16.7%, ≥about 20.0%, ≥about 25.0%, ≥about 30.0%, ≥about33.4%, ≥about 35.0%, ≥about 40.0%, ≥about 45.0%, ≥about 50.0%, ≥about55.0%, ≥about 60.0%, ≥about 65.0%, ≥about 66.7%, ≥about 70.0%, ≥about75.0%, ≥about 80.0%, ≥about 83.3%, ≥about 85.0%, ≥about 90.0%, ≥about95.0%, or about 100%. Ranges expressly disclosed include combinations ofthe above-enumerated values, e.g., about 0.0% to about 100%, about 1.0%to about 100%, about 5.0% to about 100%, about 10% to about 100%, about0.0% to about 40.0%, about 40.0% to about 100%, about 5% to about 40%,etc.

The zeolite may have a cation concentration comprising one or morecations. As understood herein, where the zeolite has a specific cationconcentration of less than 100%, e.g., a potassium cation concentrationof 50%, the zeolite may also contain at least one other cation such thatthe concentration of all the cations present totals about 100%. Thus, ifthe zeolite has a potassium cation concentration of about 50%, thezeolite may have one or more other cations at a concentration of about50%, e.g., a sodium cation concentration of about 50%, a sodium cationconcentration of about 25% and a lithium cation concentration of about25%. In the case of a zeolite containing divalent cations (such ascalcium cations (Ca²⁺), magnesium cations (Mg²⁺), barium cations (Ba²⁺),strontium cations (Sr²⁺) and copper cations (Cu²⁺)) it is understoodthat the number of divalent cations required to balance the charge istwice smaller than the number of monovalent cations (such as potassiumcations (K⁺), sodium cations (Na^(t)), lithium cations (Li^(t)), cesiumcations (Cs⁺), rubidium cations (Rb⁺), silver cations (Ag⁺) or protons(H⁺)). For example, if the zeolite has a potassium cation concentrationof about 50%, the zeolite may have one or more other cations, e.g., asodium cation concentration of about 50%, or calcium cationconcentration of about 25%.

Details regarding specific processes for CO₂-adsorption are providedbelow.

A. Pressure Swing Adsorption (PSA) Processes

In another embodiment, a PSA process for separating CO₂ from a feed gasmixture is provided. The PSA process may include subjecting the feed gasmixture comprising CO₂ to an adsorption step by introducing the feed gasmixture into a feed input end of an adsorbent bed. The feed gas mixturemay be natural gas, syngas, flue gas as well as other streams containingCO₂. Typical natural gas mixtures contain CH₄ and higher hydrocarbons(C₂H₆, C₃H₈, C₄H₁₀ etc), as well as acid gases (CO₂ and H₂₅), N₂ andH₂O. The amount of water in the natural gas mixture depends on priordehydration processing to remove H₂O. Typical syngas mixtures containH₂, CO, CO₂, CH₄, COS and H₂S. Typical flue gas mixtures contain N₂,CO₂, H₂O, O₂, SO₂. The adsorbent bed may comprise a feed input end, aproduct output end and an adsorbent material selective for adsorbingCO₂. Additionally, the adsorbent bed may be operated at a first pressureand at a first temperature wherein at least a portion of the CO₂ in thefeed gas mixture is adsorbed by the adsorbent bed and wherein a gaseousproduct depleted in CO₂ exits the product output end of the adsorbentbed.

The first temperature may be ≥about −30° C., ≥about −25° C., ≥about −20°C., ≥about-15° C., ≥about −10° C., ≥about −5° C., ≥about 0° C., ≥about5° C., ≥about 10° C., ≥about 15° C., ≥about 20° C., ≥about 25° C.,≥about 30° C., ≥about 35° C., ≥about 40° C., ≥about 45° C., ≥about 50°C., ≥about 55° C., ≥about 60° C., ≥about 65° C., ≥about 70° C., ≥about75° C., ≥about 80° C., ≥about 85° C., ≥about 90° C., ≥about 95° C., or≥about 100° C. In particular, the first temperature may be ≥about 25° C.Additionally or alternatively, the first temperature may be ≤about −30°C., ≤about −25° C., ≤about −20° C., ≤about −15° C., ≤about −10° C.,≤about −5° C., ≤about 0° C., ≤about 5° C., ≤about 10° C., ≤about 15° C.,≤about 20° C., ≤about 25° C., ≤about 30° C., ≤about 35° C., ≤about 40°C., ≤about 45° C., ≤about 50° C., ≤about 55° C., ≤about 60° C., ≤about65° C., ≤about 70° C., ≤about 75° C., ≤about 80° C., ≤about 85° C.,≤about 90° C., ≤about 95° C., or ≤about 100° C. Ranges expresslydisclosed include combinations of the above-enumerated upper and lowerlimits, e.g., about −30° C. to about 100° C., about −25° C. to about 95°C., about −20° C. to about 80° C., about 0° C. to about 50° C., about10° C. to about 30° C. In particular, the first temperature is about-20°C. to about 80° C., about 0° C. to about 50° C. or about 10° C. to about30° C.

The first pressure in combination with the above described firsttemperatures may be such that the partial pressure of CO₂ may be ≥about1 bar, ≥about 2 bar, ≥about 3 bar, ≥about 4 bar, ≥about 5 bar, ≥about 6bar, ≥about 7 bar, ≥about 8 bar, ≥about 9 bar, ≥about 10 bar, ≥about 12bar, ≥about 15 bar, ≥about 16 bar, ≥about 18 bar, ≥about 20 bar, ≥about22 bar, ≥about 24 bar, ≥about 25 bar, ≥about 26 bar, ≥about 28 bar, or≥about 30 bar. In particular, the first pressure in combination with theabove described first temperatures may be such that the partial pressureof CO₂ is ≥about 5 bar or ≥about 25 bar. Additionally or alternatively,the first pressure in combination with the above described firsttemperatures may be such that the partial pressure of CO₂ is ≤about 1bar, ≤about 2 bar, ≤about 3 bar, ≤about 4 bar, ≤about 5 bar, ≤about 6bar, ≤about 7 bar, ≤about 8 bar, ≤about 9 bar, ≤about 10 bar, ≤about 12bar, ≤about 15 bar, ≤about 16 bar, ≤about 18 bar, ≤about 20 bar, ≤about22 bar, ≤about 24 bar, ≤about 25 bar, ≤about 26 bar, ≤about 28 bar, or≤about 30 bar. Ranges expressly disclosed include combinations of theabove-enumerated upper and lower limits, e.g., about 1 bar to about 30bar, about 2 bar to about 28 bar, about 3 bar to about 25 bar, about 3bar to about 10 bar, about 15 bar to about 25 bar. In particular, thefirst pressure in combination with the above described firsttemperatures may be such that the partial pressure of CO₂ is about 3 barto about 25 bar, about 3 bar to about 10 bar, about 3 bar to about 7bar, about 15 bar to about 25 bar, or about 18 bar to about 22 bar.

In various aspects, the PSA process may further include stopping theintroduction of the feed gas mixture to the adsorbent bed beforebreakthrough of CO₂ from the product output end of the adsorbent bed,reducing the pressure in the adsorption bed to a second pressure, whichmay be lower than the first pressure, resulting in desorption of atleast a portion of CO₂ from the adsorbent bed, and recovering at least aportion of CO₂ from the adsorbent bed. The second pressure may be suchthat the partial pressure of CO₂ is ≥about 0.1 bar, ≥about 0.2 bar,≥about 0.3 bar, ≥about 0.4 bar, ≥about 0.5 bar, ≥about 0.6 bar, ≥about0.7 bar, ≥about 0.8 bar, ≥about 0.9 bar, ≥about 1 bar, ≥about 2 bar,≥about 3 bar, ≥about 4 bar, ≥about 6 bar, ≥about 7 bar, ≥about 8 bar,≥about 9 bar, or ≥about 10 bar. In particular, the second pressure maybe such that the partial pressure of CO₂ is ≥about 1 bar. Additionallyor alternatively, the second pressure may be such that the partialpressure of CO₂ is ≤about 0.1 bar, ≤about 0.2 bar, ≤about 0.3 bar,≤about 0.4 bar, ≤about 0.5 bar, ≤about 0.6 bar, ≤about 0.7 bar, ≤about0.8 bar, ≤about 0.9 bar, ≤about 1 bar, ≤about 2 bar, ≤about 3 bar,≤about 4 bar, ≤about 6 bar, ≤about 7 bar, ≤about 8 bar, ≤about 9 bar, or≤about 10 bar. Ranges expressly disclosed include combinations of theabove-enumerated upper and lower limits, e.g., about 0.1 bar to about 10bar, about 0.3 bar to about 9 bar, about 0.5 bar to about 5 bar, about0.5 bar to about 2 bar, about 1 bar to about 5 bar, etc. In particular,the second pressure may be such that the partial pressure of CO₂ isabout 0.5 bar to about 2 bar, about 1 bar to about 5 bar, or about 0.9bar to about 3 bar.

In various aspects, the adsorbent material may comprise a zeolite havinga Si/Al ratio above about 100 (e.g. above about 200, above about 400,above about 600, etc.) and a framework structure selected from the groupconsisting of AFT, AFX, DAC, EMT, EUO, IMF, ITH, ITT, KFI, LAU, MFS,MRE, MTT, MWW, NES, PAU, RRO, SFF, STF, STI, SZR, TER, TON, TSC, TUN,VFI, and a combination thereof. Additionally or alternatively, thesezeolites may include a cation concentration of less than about 10%, lessthan about 5%, less than about 1%, less than about 0.1%, or about 0%.

Additionally or alternatively, the adsorbent material may comprise azeolite with a framework structure selected from the group consisting ofCAS, EMT, FAU, HEU, IRR, IRY, ITT, LTA, RWY, TSC and VFI, and acombination thereof, having (i) a Si/Al ratio of about 5 to about 100,about 5 to about 90, about 5 to about 85, about 5 to about 70 or about 5to about 50; and/or (ii) a cation concentration (e.g., potassium cation,sodium cation) of about 0% to about 100%, about 5% to about 100%, about10% to about 100%, about 40% to about 100%, about 60% to about 100% orabout 70% to about 100%.

Additionally or alternatively, the adsorbent material may comprise azeolite having a Si/Al ratio above about 100 (e.g. above about 200,above about 400, above about 600, etc.) and a framework structureselected from the group consisting of AFT, AFX, KFI, PAU, TSC, and acombination thereof. Additionally or alternatively, these zeolites mayinclude a cation concentration of less than about 10%, less than about5%, less than about 1%, less than about 0.1%, or about 0%.

Additionally or alternatively, the adsorbent material may comprise azeolite with a framework structure selected from the group consisting ofLTA, TSC, and a combination thereof, having (i) a Si/Al ratio of about40 to about 60 or about 50; and/or a (ii) a cation concentration (e.g.,potassium cation, sodium cation) of about 50% to about 90%, about 50% toabout 80% or about 60% to about 70%.

Additionally or alternatively, the above mentioned adsorbent materialsmay not include a zeolite with a framework structure selected from thegroup consisting of CHA, FAU, LTA, RHO and a combination thereof.

Additionally or alternatively, the adsorbent material may comprise azeolite having a Si/Al ratio of between about 5 and about 45 (e.g.,about 6, about 10, about 20, about 30, about 40, etc.) and with aframework structure selected from the group consisting of CHA, FAU, FER,LTA, MFI, RHO, UFI, and a combination thereof. Additionally oralternatively, the adsorbent material may comprise a zeolite having aSi/Al ratio of between about 5 and about 45 (e.g., about 6, about 10,about 20, about 30, about 40, etc.) and with a framework structureselected from the group consisting of CHA, FAU, LTA, RHO, and acombination thereof. Additionally or alternatively, these zeolites mayinclude a cation concentration of less than about 10%, less than about5%, less than about 1%, less than about 0.1%, or about 0%.

Additionally or alternatively, the adsorbent material may have a workingcapacity of ≥about 1.0 mmol/cc, ≥about 2.0 mmol/cc, ≥about 3.0 mmol/cc,≥about 4.0 mmol/cc, ≥about 5.0 mmol/cc, ≥about 6.0 mmol/cc, ≥about 7.0mmol/cc, ≥about 8.0 mmol/cc, ≥about 9.0 mmol/cc, ≥about 10.0 mmol/cc,≥about 11.0 mmol/cc, ≥about 12.0 mmol/cc, ≥about 13.0 mmol/cc, ≥about14.0 mmol/cc, ≥about 15.0 mmol/cc, ≥about 16.0 mmol/cc, ≥about 17.0mmol/cc, ≥about 18.0 mmol/cc, ≥about 19.0 mmol/cc, or ≥about 20.0mmol/cc. Additionally or alternatively, the adsorbent material may havea working capacity of ≤about 1.0 mmol/cc, ≤about 2.0 mmol/cc, ≤about 3.0mmol/cc, ≤about 4.0 mmol/cc, ≤about 5.0 mmol/cc, ≤about 6.0 mmol/cc,≤about 7.0 mmol/cc, ≤about 8.0 mmol/cc, ≤about 9.0 mmol/cc, ≤about 10.0mmol/cc, ≤about 11.0 mmol/cc, ≤about 12.0 mmol/cc, ≤about 13.0 mmol/cc,≤about 14.0 mmol/cc, ≤about 15.0 mmol/cc, ≤about 16.0 mmol/cc, ≤about17.0 mmol/cc, ≤about 18.0 mmol/cc, ≤about 19.0 mmol/cc, or ≤about 20.0mmol/cc. Ranges expressly disclosed include combinations of theabove-enumerated values, e.g., about 1.0 mmol/cc to about 20.0 mmol/cc,about 1.0 mmol/cc to about 16.0 mmol/cc, about 2.0 mmol/cc to about 15.0mmol/cc, about 3.0 mmol/cc to about 12.0 mmol/cc, etc. In particular,the adsorbent material described herein may have a working capacity ofabout 2.0 mmol/cc to about 15.0 mmol/cc or about 3.0 mmol/cc to about12.0 mmol/cc.

Additionally or alternatively, the adsorbent material may have anaverage heat of adsorption of ≥about 15 kJ/mol, ≥about 16 kJ/mol, ≥about18 kJ/mol, ≥about 20 kJ/mol, ≥about 22 kJ/mol, ≥about 24 kJ/mol, ≥about26 kJ/mol, ≥about 28 kJ/mol, ≥about 30 kJ/mol, ≥about 32 kJ/mol, ≥about34 kJ/mol, ≥about 36 kJ/mol, ≥about 38 kJ/mol or ≥about 40 kJ/mol.Additionally or alternatively, the adsorbent material may have anaverage heat of adsorption of ≤about 15 kJ/mol, ≤about 16 kJ/mol, ≤about18 kJ/mol, ≤about 20 kJ/mol, ≤about 22 kJ/mol, ≤about 24 kJ/mol, ≤about26 kJ/mol, ≤about 28 kJ/mol, ≤about 30 kJ/mol, ≤about 32 kJ/mol, ≤about34 kJ/mol, ≤about 36 kJ/mol, ≤about 38 kJ/mol or ≤about 40 kJ/mol.Ranges expressly disclosed include combinations of the above-enumeratedvalues, e.g., about 15 kJ/mol to about 40 kJ/mol, about 18 kJ/mol toabout 38 kJ/mol, about 20 kJ/mol to about 36 kJ/mol, about 22 kJ/mol toabout 34 kJ/mol, etc. In particular, the adsorbent material may have anaverage heat of adsorption of about 20 kJ/mol to about 36 kJ/mol orabout 22 kJ/mol to about 34 kJ/mol.

In various aspects, an adsorbent material comprising one or more of thefollowing: (i) a zeolite having a Si/Al ratio above about 100 and aframework structure selected from the group consisting of AFT, AFX, DAC,EMT, EUO, IMF, ITH, ITT, KFI, LAU, MFS, MRE, MTT, MWW, NES, PAU, RRO,SFF, STF, STI, SZR, TER, TON, TSC, TUN, VFI, and a combination thereof;or (ii) a zeolite with a framework structure selected from the groupconsisting of CAS, EMT, FAU, HEU, IRR, IRY, ITT, LTA, RWY, TSC and VFI,and a combination thereof, having: (a) a Si/Al ratio of about 5 to about85; and/or (b) a potassium cation concentration of about 5% to about100%, for use in a PSA process for separating CO₂ from a feed gasmixture is provided.

In various aspects, an adsorbent material comprising a zeolite having aSi/Al ratio of between about 5 and about 45 and with a frameworkstructure selected from the group consisting of CHA, FAU, FER, LTA, MFI,RHO, UFI, and a combination thereof, for use in a PSA process forseparating CO₂ from a feed gas mixture is provided.

Nonlimiting examples of suitable zeolites for use in the PSA describedherein are those which are provided below in Table 6.

TABLE 6 Zeolites AFT_Si LTA_50_67 AFX_Si MFI_Si CAS_25_83 MFS_SiCAS_50_17 MRE_Si CHA_Si MTT_Si DAC_Si MWW_Si EMT_Si NES_Si EMT_50_100PAU_Si EUO_Si RHO_Si FAU_Si RRO_Si FAU_50_67 RWY_5_100 FER_Si RWY_10_100HEU_50_100 SFF_Si IMF_Si STF_Si IRR_10_100 STI_Si IRR_50_100 SZR_SiIRY_10_100 TER_Si IRY_50_100 TON_Si ITH_Si TSC_Si ITT_Si TSC_50_83ITT_10_100 TUN_Si KFI_Si UFI_Si LAU_Si VFI_Si LTA_Si VFI_10_100

B. Pressure Temperature Swing Adsorption (PTSA) Processes

In another embodiment, a PTSA process for separating CO₂ from a feed gasmixture is provided. The PTSA process may include subjecting the feedgas mixture comprising CO₂ to an adsorption step by introducing the feedgas mixture into a feed input end of an adsorbent bed. The feed gasmixture may be natural gas, syngas, flue gas as well as other streamscontaining CO₂. Typical natural gas mixtures contain CH₄ and higherhydrocarbons (C₂H₆, C₃H₈, etc), as well as acid gases (CO₂ and H₂S), N₂and H₂O. The amount of water in the natural gas mixture depends on priordehydration processing to remove H₂O. Typical syngas mixtures containH₂, CO, CO₂, CH₄, COS and H₂S. Typical flue gas mixtures contain N₂,CO₂, H₂O, O₂, SO₂. The adsorbent bed may comprise a feed input end, aproduct output end and an adsorbent material selective for adsorbingCO₂. Additionally, the adsorbent bed may be operated at a first pressureand at a first temperature wherein at least a portion of the CO₂ in thefeed gas mixture is adsorbed by the adsorbent bed and wherein a gaseousproduct depleted in CO₂ exits the product output end of the adsorbentbed.

The first temperature may be ≥about −30° C., ≥about −25° C., ≥about −20°C., ≥about-15° C., ≥about −10° C., ≥about −5° C., ≥about 0° C., ≥about5° C., ≥about 10° C., ≥about 15° C., ≥about 20° C., ≥about 25° C.,≥about 30° C., ≥about 35° C., ≥about 40° C., ≥about 45° C., ≥about 50°C., ≥about 55° C., ≥about 60° C., ≥about 65° C., ≥about 70° C., ≥about75° C., ≥about 80° C., ≥about 85° C., ≥about 90° C., ≥about 95° C., or≥about 100° C. In particular, the first temperature may be ≥about 25° C.Additionally or alternatively, the first temperature may be ≤about −30°C., ≤about −25° C., ≤about −20° C., ≤about −15° C., ≤about −10° C.,≤about −5° C., ≤about 0° C., ≤about 5° C., ≤about 10° C., ≤about 15° C.,≤about 20° C., ≤about 25° C., ≤about 30° C., ≤about 35° C., ≤about 40°C., ≤about 45° C., ≤about 50° C., ≤about 55° C., ≤about 60° C., ≤about65° C., ≤about 70° C., ≤about 75° C., ≤about 80° C., ≤about 85° C.,≤about 90° C., ≤about 95° C., or ≤about 100° C. Ranges expresslydisclosed include combinations of the above-enumerated upper and lowerlimits, e.g., about −30° C. to about 100° C., about 25° C. to about 95°C., about −20° C. to about 80° C., about 0° C. to about 50° C., about10° C. to about 30° C. In particular, the first temperature is about-20°C. to about 80° C., about 0° C. to about 50° C. or about 10° C. to about30° C.

The first pressure in combination with the above described firsttemperatures may be such that the partial pressure of CO₂ may be ≥about1 bar, ≥about 2 bar, ≥about 3 bar, ≥about 4 bar, ≥about 5 bar, ≥about 6bar, ≥about 7 bar, ≥about 8 bar, ≥about 9 bar, ≥about 10 bar, ≥about 12bar, ≥about 15 bar, ≥about 16 bar, ≥about 18 bar, ≥about 20 bar, ≥about22 bar, ≥about 24 bar, ≥about 25 bar, ≥about 26 bar, ≥about 28 bar, or≥about 30 bar. In particular, the first pressure in combination with theabove described first temperatures may be such that the partial pressureof CO₂ is ≥about 5 bar or ≥about 25 bar. Additionally or alternatively,the first pressure in combination with the above described firsttemperatures may be such that the partial pressure of CO₂ is ≤about 1bar, ≤about 2 bar, ≤about 3 bar, ≤about 4 bar, ≤about 5 bar, ≤about 6bar, ≤about 7 bar, ≤about 8 bar, ≤about 9 bar, ≤about 10 bar, ≤about 12bar, ≤about 15 bar, ≤about 16 bar, ≤about 18 bar, ≤about 20 bar, ≤about22 bar, ≤about 24 bar, ≤about 25 bar, ≤about 26 bar, ≤about 28 bar, or≤about 30 bar. Ranges expressly disclosed include combinations of theabove-enumerated upper and lower limits, e.g., about 1 bar to about 30bar, about 2 bar to about 28 bar, about 3 bar to about 25 bar, about 3bar to about 10 bar, about 15 bar to about 25 bar. In particular, afirst pressure in combination with the above described firsttemperatures may be such that the partial pressure of CO₂ is about 3 barto about 25 bar, about 3 bar to about 10 bar, about 3 bar to about 7bar, about 15 bar to about 25 bar, or about 18 bar to about 22 bar.

In various aspects, the PTSA process may further include stopping theintroduction of the feed gas mixture to the adsorbent bed beforebreakthrough of CO₂ from the product output end of the adsorbent bed andheating the adsorbent bed to a second temperature, which may be higherthan the first temperature, resulting in desorption of at least aportion of CO₂ from the adsorbent bed and recovering at least a firstportion of CO₂. The second temperature may be ≥about 30° C., ≥about 35°C., ≥about 40° C., ≥about 45° C., ≥about 50° C., ≥about 55° C., ≥about60° C., ≥about 65° C., ≥about 70° C., ≥about 75° C., ≥about 80° C.,≥about 85° C., ≥about 90° C., ≥about 95° C., ≥about 100° C., ≥about 105°C., ≥about 110° C., ≥about 115° C., ≥about 120° C., ≥about 125° C.,≥about 130° C., ≥about 135° C., ≥about 140° C., ≥about 145° C., ≥about150° C., ≥about 155° C., ≥about 160° C., ≥about 165° C., ≥about 170° C.,≥about 175° C., ≥about 180° C., ≥about 185° C., ≥about 190° C., ≥about195° C., or ≥about 200° C. In particular, the second temperature may be≥about 95° C. Additionally or alternatively, the second temperature maybe ≤about 30° C., ≤about 35° C., ≤about 40° C., ≤about 45° C., ≤about50° C., ≤about 55° C., ≤about 60° C., ≤about 65° C., ≤about 70° C.,≤about 75° C., ≤about 80° C., ≤about 85° C., ≤about 90° C., ≤about 95°C., ≤about 100° C., ≤about 105° C., ≤about 110° C., ≤about 115° C.,≤about 120° C., ≤about 125° C., ≤about 130° C., ≤about 135° C., ≤about140° C., ≤about 145° C., ≤about 150° C., ≤about 155° C., ≤about 160° C.,≤about 165° C., ≤about 170° C., ≤about 175° C., ≤about 180° C., ≤about185° C., ≤about 190° C., ≤about 195° C., or ≤about 200° C. Rangesexpressly disclosed include combinations of the above-enumerated upperand lower limits, e.g., about 30° C. to about 200° C., about 50° C. toabout 150° C., about 55° C. to about 125° C., about 75° C. to about 120°C., about 80° C. to about 110° C., etc. In particular, the secondtemperature is about 50° C. to about 150° C., about 75° C. to about 120°C. or about 80° C. to about 110° C.

Additionally or alternatively, the PTSA process may further includereducing the pressure of the adsorbent bed to a second pressure, whichmay be lower than the first pressure, and recovering a second portion ofCO₂. The second pressure in combination with above described secondtemperature may be such that the partial pressure of CO₂ is ≥about 0.1bar, ≥about 0.2 bar, ≥about 0.3 bar, ≥about 0.4 bar, ≥about 0.5 bar,≥about 0.6 bar, ≥about 0.7 bar, ≥about 0.8 bar, ≥about 0.9 bar, ≥about 1bar, ≥about 2 bar, ≥about 3 bar, ≥about 4 bar, ≥about 6 bar, ≥about 7bar, ≥about 8 bar, ≥about 9 bar, or ≥about 10 bar. In particular, thesecond pressure in combination with above described second temperaturemay be such that the partial pressure of CO₂ is ≥about 1 bar.Additionally or alternatively, the second pressure in combination withabove described second temperature may be such that the partial pressureof CO₂ is ≤about 0.1 bar, ≤about 0.2 bar, ≤about 0.3 bar, ≤about 0.4bar, ≤about 0.5 bar, ≤about 0.6 bar, ≤about 0.7 bar, ≤about 0.8 bar,≤about 0.9 bar, ≤about 1 bar, ≤about 2 bar, ≤about 3 bar, ≤about 4 bar,≤about 6 bar, ≤about 7 bar, ≤about 8 bar, ≤about 9 bar, or ≤about 10bar. Ranges expressly disclosed include combinations of theabove-enumerated upper and lower limits, e.g., about 0.1 bar to about 10bar, about 0.3 bar to about 9 bar, about 0.5 bar to about 5 bar, about0.5 bar to about 2 bar, about 1 bar to about 5 bar, etc. In particular,the second pressure in combination with above described secondtemperature may be such that the partial pressure of CO₂ is about 0.5bar to about 2 bar, about 1 bar to about 5 bar, or about 0.9 bar toabout 3 bar.

In various aspects, the adsorbent material may comprise a zeolite havinga Si/Al ratio above about 100 (e.g. above about 200, above about 400,above about 600, etc.) and a framework structure selected from the groupconsisting of AFT, AFX, CAS, DAC, HEU, IMF, ITH, KFI, LAU, MFS, MTT,PAU, RRO, SFF, STF, SXR, TER, TON, TUN, and a combination thereof.Additionally or alternatively, these zeolites may include a cationconcentration of less than about 10%, less than about 5%, less thanabout 1%, less than about 0.1%, or about 0%.

Additionally or alternatively, the adsorbent material may comprise azeolite with a framework structure selected from the group consisting ofAFT, AFX, CHA, EMT, EUO, FAU, IRR, IRY, ITT, KFI, LTA, MRE, MWW, NES,PAU, RHO, RWY, SFF, STI, TSC, UFI, VFI, having (i) a Si/Al ratio ofabout 3 to about 100, about 3 to 75, about 5 to about 90, about 5 toabout 85, about 5 to about 70, about 5 to about 60 or about 5 to about50; and/or (ii) a cation concentration (e.g., potassium cation, sodiumcation) of about 0% to about 100%, about 1% to about 100%, about 5% toabout 100%, about 10% to about 100%, about 40% to about 100%, about 60%to about 100% or about 70% to about 100%.

Additionally or alternatively, the adsorbent material may comprise azeolite having a Si/Al ratio above about 100 (e.g. above about 200,above about 400, above about 600, etc.) and a framework structureselected from the group consisting of AFT, AFX, KFI, PAU, TSC, and acombination thereof. Additionally or alternatively, these zeolites mayinclude a cation concentration of less than about 10%, less than about5%, less than about 1%, less than about 0.1%, or about 0%.

Additionally or alternatively, the adsorbent material may comprise azeolite with a framework structure selected from the group consisting ofAFT, AFX, CHA, KFI, LTA, PAU, RHO, TSC, UFI, and a combination thereof,having (i) a Si/Al ratio of about 5 to about 60 or about 10 to about 50;and/or a (ii) a cation concentration (e.g., potassium cation, sodiumcation) of about 1% to about 100%, about 30% to about 100%, or about 50%to about 100%.

Additionally or alternatively, the above mentioned adsorbent materialsmay not include a zeolite with a framework structure selected from thegroup consisting of CHA, FAU, LTA, RHO and a combination thereof.

Additionally or alternatively, the adsorbent material may comprise azeolite having a Si/Al ratio of between about 5 and about 45 (e.g.,about 6, about 10, about 20, about 30, about 40, etc.) and with aframework structure selected from the group consisting of CHA, FAU, FER,LTA, MFI, RHO, UFI, and a combination thereof. Additionally oralternatively, the adsorbent material may comprise a zeolite having aSi/Al ratio of between about 5 and about 45 (e.g., about 6, about 10,about 20, about 30, about 40, etc.) and with a framework structureselected from the group consisting of CHA, FAU, LTA, RHO, and acombination thereof. Additionally or alternatively, these zeolites mayinclude a cation concentration of less than about 10%, less than about5%, less than about 1%, less than about 0.1%, or about 0%.

Additionally or alternatively, the adsorbent material may have a workingcapacity of ≥about 1.0 mmol/cc, ≥about 2.0 mmol/cc, ≥about 3.0 mmol/cc,≥about 4.0 mmol/cc, ≥about 5.0 mmol/cc, ≥about 6.0 mmol/cc, ≥about 7.0mmol/cc, ≥about 8.0 mmol/cc, ≥about 9.0 mmol/cc, ≥about 10.0 mmol/cc,≥about 11.0 mmol/cc, ≥about 12.0 mmol/cc, ≥about 13.0 mmol/cc, ≥about14.0 mmol/cc, ≥about 15.0 mmol/cc, ≥about 16.0 mmol/cc, ≥about 17.0mmol/cc, ≥about 18.0 mmol/cc, ≥about 19.0 mmol/cc, or ≥about 20.0mmol/cc. Additionally or alternatively, the adsorbent material may havea working capacity of ≤about 1.0 mmol/cc, ≤about 2.0 mmol/cc, ≤about 3.0mmol/cc, ≤about 4.0 mmol/cc, ≤about 5.0 mmol/cc, ≤about 6.0 mmol/cc,≤about 7.0 mmol/cc, ≤about 8.0 mmol/cc, ≤about 9.0 mmol/cc, ≤about 10.0mmol/cc, ≤about 11.0 mmol/cc, ≤about 12.0 mmol/cc, ≤about 13.0 mmol/cc,≤about 14.0 mmol/cc, ≤about 15.0 mmol/cc, ≤about 16.0 mmol/cc, ≤about17.0 mmol/cc, ≤about 18.0 mmol/cc, ≤about 19.0 mmol/cc, or ≤about 20.0mmol/cc. Ranges expressly disclosed include combinations of theabove-enumerated values, e.g., about 1.0 mmol/cc to about 20.0 mmol/cc,about 1.0 mmol/cc to about 16.0 mmol/cc, about 2.0 mmol/cc to about 15.0mmol/cc, about 3.0 mmol/cc to about 12.0 mmol/cc, about 3.0 mmol/cc toabout 17.0 mmol/cc, about 5.0 mmol/cc to about 15.0 mmol/cc, etc. Inparticular, the adsorbent material may have a working capacity of about3.0 mmol/cc to about 17.0 mmol/cc or about 5.0 mmol/cc to about 15.0mmol/cc.

Additionally or alternatively, the adsorbent material may have anaverage heat of adsorption of ≥about 15 kJ/mol, ≥about 16 kJ/mol, ≥about18 kJ/mol, ≥about 20 kJ/mol, ≥about 22 kJ/mol, ≥about 24 kJ/mol, ≥about25 kJ/mol, ≥about 26 kJ/mol, ≥about 28 kJ/mol, ≥about 30 kJ/mol, ≥about32 kJ/mol, ≥about 34 kJ/mol, ≥about 35 kJ/mol, ≥about 36 kJ/mol, ≥about38 kJ/mol or ≥about 40 kJ/mol. Additionally or alternatively, theadsorbent may have an average heat of adsorption of ≤about 15 kJ/mol,≤about 16 kJ/mol, ≤about 18 kJ/mol, ≤about 20 kJ/mol, ≤about 22 kJ/mol,≤about 24 kJ/mol, ≤about 25 kJ/mol, ≤about 26 kJ/mol, ≤about 28 kJ/mol,≤about 30 kJ/mol, ≤about 32 kJ/mol, ≤about 34 kJ/mol, ≤about 35 kJ/mol,≤about 36 kJ/mol, ≤about 38 kJ/mol or ≤about 40 kJ/mol. Ranges expresslydisclosed include combinations of the above-enumerated values, e.g.,about 15 kJ/mol to about 40 kJ/mol, about 18 kJ/mol to about 38 kJ/mol,about 20 kJ/mol to about 36 kJ/mol, about 22 kJ/mol to about 36 kJ/mol,about 24 kJ/mol to about 36 kJ/mol, about 25 kJ/mol to about 35 kJ/moletc. In particular, the adsorbent material may have an average heat ofadsorption of about 20 kJ/mol to about 38 kJ/mol, about 22 kJ/mol toabout 36 kJ/mol or about 24 kJ/mol to about 36 kJ/mol.

In various aspects, an adsorbent material comprising one or more of thefollowing: (i) a zeolite having a Si/Al ratio above about 100 and aframework structure selected from the group consisting of AFT, AFX, CAS,DAC, HEU, IMF, ITH, KFI, LAU, MFS, MTT, PAU, RRO, SFF, STF, SXR, TER,TON, TUN, and a combination thereof; or (ii) a zeolite with a frameworkstructure selected from the group consisting of AFT, AFX, CHA, EMT, EUO,FAU, IRR, IRY, ITT, KFI, LTA, MRE, MWW, NES, PAU, RHO, RWY, SFF, STI,TSC, UFI, VFI, and a combination thereof, having: (a) a Si/Al ratio ofabout 3 to about 100; and/or (b) a potassium cation concentration ofabout 1% to about 100%, for use in a PTSA process for separating CO₂from a feed gas mixture is provided.

Nonlimiting examples of suitable zeolites for use in the PTSA describedherein are those which are provided below in Table 7.

TABLE 7 Zeolites AFT_Si MFI_Si AFT_50_33 MFS_Si AFX_Si MRE_10_100AFX_50_0 MTT_Si CAS_Si MWW_25_100 CHA_Si MWW_50_100 CHA_25_50 NES_50_100DAC_Si PAU_Si EMT_5_33 PAU_50_67 EMT_10_100 RHO_Si EUO_25_100 RHO_25_83FAU_5_83 RRO_Si FER_Si RWY_3_17 HEU_Si SFF_Si IMF_Si SFF_50_100 IRR_5_50STF_Si IRR_10_33 STI_10_100 IRY_3_0 SZR_Si IRY_10_67 TER_Si ITH_SiTON_Si ITT_5_50 TSC_10_17 ITT_25_50 TSC_25_33 KFI_Si TUN_Si KFI_25_100UFI_Si LAU_Si UFI_25_100 LTA_10_33 VFI_1_0 LTA_50_83

C. Vacuum Swing Adsorption (VSA) Processes

In another embodiment, a VSA process for separating CO₂ from a feed gasmixture is provided. The VSA process may include subjecting the feed gasmixture comprising CO₂ to an adsorption step by introducing the feed gasmixture into a feed input end of an adsorbent bed. The feed gas mixturemay be natural gas, syngas, flue gas as well as other streams containingCO₂. Typical natural gas mixtures contain CH₄ and higher hydrocarbons(C₂H₆, C₃H₈, C₄H₁₀ etc), as well as acid gases (CO₂ and H₂S), N₂ andH₂O. The amount of water in the natural gas mixture depends on priordehydration processing to remove H₂O. Typical syngas mixtures containH₂, CO, CO₂, CH₄, COS and H₂S. Typical flue gas mixtures contain N₂,CO₂, H₂O, O₂, SO₂. The adsorbent bed may comprise a feed input end, aproduct output end and an adsorbent material selective for adsorbingCO₂. Additionally, the adsorbent bed may be operated at a first pressureand at a first temperature wherein at least a portion of the CO₂ in thefeed gas mixture is adsorbed by the adsorbent bed and wherein a gaseousproduct depleted in CO₂ exits the product output end of the adsorbentbed.

The first temperature may be ≥about −30° C., ≥about −25° C., ≥about −20°C., ≥about-15° C., ≥about −10° C., ≥about −5° C., ≥about 0° C., ≥about5° C., ≥about 10° C., ≥about 15° C., ≥about 20° C., ≥about 25° C.,≥about 30° C., ≥about 35° C., ≥about 40° C., ≥about 45° C., ≥about 50°C., ≥about 55° C., ≥about 60° C., ≥about 65° C., ≥about 70° C., ≥about75° C., ≥about 80° C., ≥about 85° C., ≥about 90° C., ≥about 95° C., or≥about 100° C. In particular, the first temperature may be ≥about 25° C.Additionally or alternatively, the first temperature may be ≤about −30°C., ≤about −25° C., ≤about −20° C., ≤about −15° C., ≤about −10° C.,≤about −5° C., ≤about 0° C., ≤about 5° C., ≤about 10° C., ≤about 15° C.,≤about 20° C., ≤about 25° C., ≤about 30° C., ≤about 35° C., ≤about 40°C., ≤about 45° C., ≤about 50° C., ≤about 55° C., ≤about 60° C., ≤about65° C., ≤about 70° C., ≤about 75° C., ≤about 80° C., ≤about 85° C.,≤about 90° C., ≤about 95° C., or ≤about 100° C. Ranges expresslydisclosed include combinations of the above-enumerated upper and lowerlimits, e.g., about −30° C. to about 100° C., about −25° C. to about 95°C., about −20° C. to about 80° C., about 0° C. to about 50° C., about10° C. to about 30° C. In particular, the first temperature is about-20°C. to about 80° C., about 0° C. to about 50° C. or about 10° C. to about30° C.

The first pressure in combination with the above described firsttemperatures may be such that the partial pressure of CO₂ may be ≥about0.1 bar, ≥about 0.2 bar, ≥about 0.3 bar, ≥about 0.4 bar, ≥about 0.5 bar,≥about 0.6 bar, ≥about 0.7 bar, ≥about 0.8 bar, ≥about 0.9 bar, ≥about 1bar, ≥about 2 bar, ≥about 3 bar, ≥about 4 bar, ≥about 6 bar, ≥about 7bar, ≥about 8 bar, ≥about 9 bar, or ≥about 10 bar. In particular, thefirst pressure in combination with the above described firsttemperatures may be such that the partial pressure of CO₂ is ≥about 1bar. Additionally or alternatively, the first pressure in combinationwith above described first temperature may be such that the partialpressure of CO₂ is ≤about 0.1 bar, ≤about 0.2 bar, ≤about 0.3 bar,≤about 0.4 bar, ≤about 0.5 bar, ≤about 0.6 bar, ≤about 0.7 bar, ≤about0.8 bar, ≤about 0.9 bar, ≤about 1 bar, ≤about 2 bar, ≤about 3 bar,≤about 4 bar, ≤about 6 bar, ≤about 7 bar, ≤about 8 bar, ≤about 9 bar, or≤about 10 bar. Ranges expressly disclosed include combinations of theabove-enumerated upper and lower limits, e.g., about 0.1 bar to about 10bar, about 0.3 bar to about 9 bar, about 0.5 bar to about 5 bar, about0.5 bar to about 3 bar, about 1 bar to about 5 bar, etc. In particular,the first pressure in combination with above described first temperaturemay be such that the partial pressure of CO₂ is about 0.5 bar to about 3bar, about 0.5 bar to about 2 bar, about 1 bar to about 5 bar, or about0.7 bar to about 2 bar.

In various aspects, the VSA process may further include stopping theintroduction of the feed gas mixture to the adsorbent bed beforebreakthrough of CO₂ from the product output end of the adsorbent bed,passing a purge gas, substantially free of CO₂, through the adsorbentbed thereby resulting in a reduction in the pressure in the adsorptionbed to a second pressure and in desorption of at least a portion of CO₂from the adsorbent bed, and recovering at least a portion of CO₂ fromthe adsorbent bed. The second pressure may be such that the partialpressure of CO₂ is ≥about 0.01 bar, ≥about 0.02 bar, ≥about 0.03 bar,≥about 0.04 bar, ≥about 0.05 bar, ≥about 0.06 bar, ≥about 0.07 bar,≥about 0.08 bar, ≥about 0.09 bar, ≥about 0.1 bar, ≥about 0.2 bar, ≥about0.3 bar, ≥about 0.4 bar, ≥about 0.5 bar, ≥about 0.6 bar, ≥about 0.7 bar,≥about 0.8 bar, ≥about 0.9 bar, ≥about 0.95 bar or about 0.99 bar. Inparticular, the second pressure may be such that the partial pressure ofCO₂ is ≥about 0.1 bar. Additionally or alternatively, the secondpressure may be such that the partial pressure of CO₂ is ≤about 0.01bar, ≤about 0.02 bar, ≤about 0.03 bar, ≤about 0.04 bar, ≤about 0.05 bar,≤about 0.06 bar, ≤about 0.07 bar, ≤about 0.08 bar, ≤about 0.09 bar,≤about 0.1 bar, ≤about 0.2 bar, ≤about 0.3 bar, ≤about 0.4 bar, ≤about0.5 bar, ≤about 0.6 bar, ≤about 0.7 bar, ≤about 0.8 bar, ≤about 0.9 bar,≤about 0.95 bar or ≤0.99 bar. Ranges expressly disclosed includecombinations of the above-enumerated upper and lower limits, e.g., about0.01 bar to about 0.99 bar, about 0.05 bar to about 0.8 bar, about 0.05bar to about 0.5 bar, about 0.07 bar to about 0.4 bar, about 0.09 bar toabout 0.2 bar, etc. In particular, the second pressure may be such thatthe partial pressure of CO₂ is about 0.05 bar to about 0.5 bar or about0.09 bar to about 0.2 bar.

In various aspects, the adsorbent material may comprise a zeolite havinga Si/Al ratio above about 100 (e.g. above about 200, above about 400,above about 600, etc.) and a framework structure selected from the groupconsisting of CAS, DAC, HEU, LAU, MTT, RRO, TON, and a combinationthereof. Additionally or alternatively, these zeolites may include acation concentration of less than about 10%, less than about 5%, lessthan about 1%, less than about 0.1%, or about 0%.

Additionally or alternatively, the adsorbent material may comprise azeolite with a framework structure selected from the group consisting ofAFT, AFX, EMT, EUO, IMF, IRR, IRY, ITH, ITT, KFI, MFS, MRE, MWW, NES,PAU, RWY, SFF, STF, STI, SZR, TER, TSC, TUN, VFI, and a combinationthereof, having (i) a Si/Al ratio of about 1 to about 100, about 1 toabout 90, about 1 to about 75, about 1 to about 60 or about 1 to about50; and/or (ii) a cation concentration (e.g., potassium cation, sodiumcation) of about 0% to about 100%, about 5% to about 100%, about 10% toabout 100%, about 10% to about 90%, about 40% to about 100%, about 60%to about 100% or about 70% to about 100%.

Additionally or alternatively, the adsorbent material may comprise azeolite with a framework structure selected from the group consisting ofAFX, AFT, KFI, PAU, TSC, and a combination thereof, having (i) a Si/Alratio of about 3 to about 60 or about 5 to about 50; and/or a (ii) acation concentration (e.g., potassium cation, sodium cation) of about 0%to about 100%, about 10% to about 100%, about 30% to about 100%, about50% to about 100%, or about 70% to about 100%.

Additionally or alternatively, the above mentioned adsorbent materialsmay not include a zeolite with a framework structure selected from thegroup consisting of CHA, FAU, LTA, RHO and a combination thereof.

Additionally or alternatively, the adsorbent material may comprise azeolite with a framework structure selected from the group consisting ofCHA, FAU, FER, LTA, MFI, RHO, UFI, and a combination thereof, having (i)a Si/Al ratio of between about 3 and about 50, about 4 to about 40,about 4 to about 30 or about 5 to about 25; and/or (ii) a cationconcentration (e.g., potassium cation, sodium cation) of about 20% toabout 100%, about 30% to about 100%, about 40% to about 100%, about 50%to about 100%, or about 70% to about 100%. Additionally oralternatively, the adsorbent material may comprise a zeolite with aframework structure selected from the group consisting of CHA, FAU, LTA,RHO, and a combination thereof, having (i) a Si/Al ratio of betweenabout 3 and about 50, about 4 to about 40, about 4 to about 30 or about5 to about 25; and/or (ii) a cation concentration (e.g., potassiumcation, sodium cation) of about 20% to about 100%, about 30% to about100%, about 40% to about 100%, about 50% to about 100%, or about 70% toabout 100%.

Additionally or alternatively, the adsorbent material may have a workingcapacity of ≥about 0.5 mmol/cc≥about 1.0 mmol/cc, ≥about 2.0 mmol/cc,≥about 3.0 mmol/cc, ≥about 4.0 mmol/cc, ≥about 5.0 mmol/cc, ≥about 6.0mmol/cc, ≥about 7.0 mmol/cc, ≥about 8.0 mmol/cc, ≥about 9.0 mmol/cc,≥about 10.0 mmol/cc, ≥about 11.0 mmol/cc, ≥about 12.0 mmol/cc, ≥about13.0 mmol/cc, ≥about 14.0 mmol/cc, ≥about 15.0 mmol/cc, ≥about 16.0mmol/cc, ≥about 17.0 mmol/cc, ≥about 18.0 mmol/cc, ≥about 19.0 mmol/cc,or ≥about 20.0 mmol/cc. Additionally or alternatively, the adsorbentmaterial may have a working capacity of ≤about 0.5 mmol/cc, ≤about 1.0mmol/cc, ≤about 2.0 mmol/cc, ≤about 3.0 mmol/cc, ≤about 4.0 mmol/cc,≤about 5.0 mmol/cc, ≤about 6.0 mmol/cc, ≤about 7.0 mmol/cc, ≤about 8.0mmol/cc, ≤about 9.0 mmol/cc, ≤about 10.0 mmol/cc, ≤about 11.0 mmol/cc,≤about 12.0 mmol/cc, ≤about 13.0 mmol/cc, ≤about 14.0 mmol/cc, ≤about15.0 mmol/cc, ≤about 16.0 mmol/cc, ≤about 17.0 mmol/cc, ≤about 18.0mmol/cc, ≤about 19.0 mmol/cc, or ≤about 20.0 mmol/cc. Ranges expresslydisclosed include combinations of the above-enumerated values, e.g.,about 0.5 mmol/cc to about 20.0 mmol/cc, about 1.0 mmol/cc to about 16.0mmol/cc, about 2.0 mmol/cc to about 15.0 mmol/cc, about 3.0 mmol/cc toabout 12.0 mmol/cc, about 3.0 mmol/cc to about 10.0 mmol/cc, about 3.0mmol/cc to about 6.0 mmol/cc etc. In particular, the adsorbent materialmay have a working capacity of about 3.0 mmol/cc to about 10.0 mmol/ccor about 3.0 mmol/cc to about 6.0 mmol/cc.

Additionally or alternatively, the adsorbent material may have anaverage heat of adsorption of ≥about 15 kJ/mol, ≥about 16 kJ/mol, ≥about18 kJ/mol, ≥about 20 kJ/mol, ≥about 22 kJ/mol, ≥about 24 kJ/mol, ≥about26 kJ/mol, ≥about 28 kJ/mol, ≥about 30 kJ/mol, ≥about 32 kJ/mol, ≥about34 kJ/mol, ≥about 36 kJ/mol, ≥about 38 kJ/mol or ≥about 40 kJ/mol.Additionally or alternatively, the adsorbent material may have anaverage heat of adsorption of ≤about 15 kJ/mol, ≤about 16 kJ/mol, ≤about18 kJ/mol, ≤about 20 kJ/mol, ≤about 22 kJ/mol, ≤about 24 kJ/mol, ≤about26 kJ/mol, ≤about 28 kJ/mol, ≤about 30 kJ/mol, ≤about 32 kJ/mol, ≤about34 kJ/mol, ≤about 36 kJ/mol, ≤about 38 kJ/mol or ≤about 40 kJ/mol.Ranges expressly disclosed include combinations of the above-enumeratedvalues, e.g., about 15 kJ/mol to about 40 kJ/mol, about 20 kJ/mol toabout 38 kJ/mol, about 22 kJ/mol to about 38 kJ/mol, about 24 kJ/mol toabout 38 kJ/mol etc. In particular, the adsorbent material for use inthe PSA process described herein may have an average heat of adsorptionof about 20 kJ/mol to about 38 kJ/mol or about 24 kJ/mol to about 38kJ/mol.

In various aspects, an adsorbent material comprising one or more of thefollowing: (i) a zeolite having a Si/Al ratio above about 100 and aframework structure selected from the group consisting of CAS, DAC, HEU,LAU, MTT, RRO, TON, and a combination thereof; or (ii) a zeolite with aframework structure selected from the group consisting of AFT, AFX, EMT,EUO, IMF, IRR, IRY, ITH, ITT, KFI, MFS, MRE, MWW, NES, PAU, RWY, SFF,STF, STI, SZR, TER, TSC, TUN, VFI, and a combination thereof, having:(a) a Si/Al ratio of about 1 to about 100; and/or (b) a potassium cationconcentration of about 0% to about 100%, for use in a VSA process forseparating CO₂ from a feed gas mixture is provided.

In various aspects, an adsorbent material comprising a zeolite with aframework structure selected from the group consisting of CHA, FAU, FER,LTA, MFI, RHO, UFI and a combination thereof, having (a) a Si/Al ratioof about 3 to about 30; and/or a potassium cation concentration of about40% to about 100%, for use in a VSA process for separating CO₂ from afeed gas mixture is provided.

Nonlimiting examples of suitable zeolites for use in the VSA describedherein are those which are provided below in Table 8.

TABLE 8 Zeolites RWY_3_17 HEU_Si IRY_3_83 MWW_10_100 FAU_5_100 SFF_25_67UFI_2S_100 CAS_Si KFI_25_100 TER_50_100 IRR_3_100 STI_10_83 EMT_5_83MFS_25_100 RHO_10_50 TUN_50_100 AFX_25_33 NES_10_67 PAU_50_33 FER_50_100VFI_1_0 ITH_25_100 AFT_25_83 LAU_Si RRO_Si MFI_50_100 CHA_25_83SZR_50_83 DAC_Si EUO_25_100 LTA_5_50 IMF_50_100 TSC_5_0 TON_Si ITT_3_50MTT_Si STF_50_100 MRE_10_100

D. Vacuum Temperature Swing Adsorption (VTSA) Processes

In another embodiment, a VTSA process for separating CO₂ from a feed gasmixture is provided. The VTSA process may include subjecting the feedgas mixture comprising CO₂ to an adsorption step by introducing the feedgas mixture into a feed input end of an adsorbent bed. The feed gasmixture may be natural gas, syngas, flue gas as well as other streamscontaining CO₂. Typical natural gas mixtures contain CH₄ and higherhydrocarbons (C₂H₆, C₃H₈, C₄H₁₀ etc), as well as acid gases (CO₂ andH₂₅), N₂ and H₂O. The amount of water in the natural gas mixture dependson prior dehydration processing to remove H₂O. Typical syngas mixturescontain H₂, CO, CO₂, CH₄, COS and H₂S. Typical flue gas mixtures containN₂, CO₂, H₂O, O₂, SO₂. The adsorbent bed may comprise a feed input end,a product output end and an adsorbent material selective for adsorbingCO₂. Additionally, the adsorbent bed may be operated at a first pressureand at a first temperature wherein at least a portion of the CO₂ in thefeed gas mixture is adsorbed by the adsorbent bed and wherein a gaseousproduct depleted in CO₂ exits the product output end of the adsorbentbed.

The first temperature may be ≥about −30° C., ≥about −25° C., ≥about −20°C., ≥about-15° C., ≥about −10° C., ≥about −5° C., ≥about 0° C., ≥about5° C., ≥about 10° C., ≥about 15° C., ≥about 20° C., ≥about 25° C.,≥about 30° C., ≥about 35° C., ≥about 40° C., ≥about 45° C., ≥about 50°C., ≥about 55° C., ≥about 60° C., ≥about 65° C., ≥about 70° C., ≥about75° C., ≥about 80° C., ≥about 85° C., ≥about 90° C., ≥about 95° C., or≥about 100° C. In particular, the first temperature may be ≥about 25° C.Additionally or alternatively, the first temperature may be ≤about −30°C., ≤about −25° C., ≤about −20° C., ≤about −15° C., ≤about −10° C.,≤about −5° C., ≤about 0° C., ≤about 5° C., ≤about 10° C., ≤about 15° C.,≤about 20° C., ≤about 25° C., ≤about 30° C., ≤about 35° C., ≤about 40°C., ≤about 45° C., ≤about 50° C., ≤about 55° C., ≤about 60° C., ≤about65° C., ≤about 70° C., ≤about 75° C., ≤about 80° C., ≤about 85° C.,≤about 90° C., ≤about 95° C., or ≤about 100° C. Ranges expresslydisclosed include combinations of the above-enumerated upper and lowerlimits, e.g., about −30° C. to about 100° C., about −25° C. to about 95°C., about −20° C. to about 80° C., about 0° C. to about 50° C., about10° C. to about 30° C. In particular, the first temperature is about-20°C. to about 80° C., about 0° C. to about 50° C. or about 10° C. to about30° C.

The first pressure in combination with the above described firsttemperatures may be such that the partial pressure of CO₂ may be ≥about0.1 bar, ≥about 0.2 bar, ≥about 0.3 bar, ≥about 0.4 bar, ≥about 0.5 bar,≥about 0.6 bar, ≥about 0.7 bar, ≥about 0.8 bar, ≥about 0.9 bar, ≥about 1bar, ≥about 2 bar, ≥about 3 bar, ≥about 4 bar, ≥about 6 bar, ≥about 7bar, ≥about 8 bar, ≥about 9 bar, or ≥about 10 bar. In particular, thefirst pressure in combination with the above described firsttemperatures may be such that the partial pressure of CO₂ is ≥about 1bar. Additionally or alternatively, the first pressure in combinationwith above described first temperature may be such that the partialpressure of CO₂ is ≤about 0.1 bar, ≤about 0.2 bar, ≤about 0.3 bar,≤about 0.4 bar, ≤about 0.5 bar, ≤about 0.6 bar, ≤about 0.7 bar, ≤about0.8 bar, ≤about 0.9 bar, ≤about 1 bar, ≤about 2 bar, ≤about 3 bar,≤about 4 bar, ≤about 6 bar, ≤about 7 bar, ≤about 8 bar, ≤about 9 bar, or≤about 10 bar. Ranges expressly disclosed include combinations of theabove-enumerated upper and lower limits, e.g., about 0.1 bar to about 10bar, about 0.3 bar to about 9 bar, about 0.5 bar to about 7 bar, about0.5 bar to about 6 bar, about 1 bar to about 5 bar, etc. In particular,the first pressure in combination with above described first temperaturemay be such that the partial pressure of CO₂ is about 0.5 bar to about 7bar, about 0.5 bar to about 6 bar, about 1 bar to about 5 bar, or about0.7 bar to about 2 bar.

In various aspects, the VTSA process may further include stopping theintroduction of the feed gas mixture to the adsorbent bed beforebreakthrough of CO₂ from the product output end of the adsorbent bed andheating the adsorbent bed to a second temperature higher than the firsttemperature and passing a purge gas, substantially free of CO₂, throughthe adsorbent bed thereby resulting in a reduction in the pressure inthe adsorption bed to a second pressure, resulting in desorption of atleast a portion of CO₂ from the adsorbent bed and recovering at least aportion of CO₂. The adsorbent bed may be heated simultaneously withpassing the purge gas through though adsorbent bed. The secondtemperature may be ≥about 30° C., ≥about 35° C., ≥about 40° C., ≥about45° C., ≥about 50° C., ≥about 55° C., ≥about 60° C., ≥about 65° C.,≥about 70° C., ≥about 75° C., ≥about 80° C., ≥about 85° C., ≥about 90°C., ≥about 95° C., ≥about 100° C., ≥about 105° C., ≥about 110° C.,≥about 115° C., ≥about 120° C., ≥about 125° C., ≥about 130° C., ≥about135° C., ≥about 140° C., ≥about 145° C., ≥about 150° C., ≥about 155° C.,≥about 160° C., ≥about 165° C., ≥about 170° C., ≥about 175° C., ≥about180° C., ≥about 185° C., ≥about 190° C., ≥about 195° C., ≥about 200° C.,≥about 205° C., ≥about 210° C., ≥about 215° C., ≥about 220° C., ≥about225° C., ≥about 250° C., ≥about 275° C., or ≥300° C. In particular, thesecond temperature may be ≥about 95° C. or ≥about 195° C. Additionallyor alternatively, the second temperature may be ≤about 30° C., ≤about35° C., ≤about 40° C., ≤about 45° C., ≤about 50° C., ≤about 55° C.,≤about 60° C., ≤about 65° C., ≤about 70° C., ≤about 75° C., ≤about 80°C., ≤about 85° C., ≤about 90° C., ≤about 95° C., ≤about 100° C., ≤about105° C., ≤about 110° C., ≤about 115° C., ≤about 120° C., ≤about 125° C.,≤about 130° C., ≤about 135° C., ≤about 140° C., ≤about 145° C., ≤about150° C., ≤about 155° C., ≤about 160° C., ≤about 165° C., ≤about 170° C.,≤about 175° C., ≤about 180° C., ≤about 185° C., ≤about 190° C., ≤about195° C., ≤about 200° C., ≤about 205° C., ≤about 210° C., ≤about 215° C.,≤about 220° C., ≤about 225° C., ≤about 250° C., ≤about 275° C., or ≤300°C. Ranges expressly disclosed include combinations of theabove-enumerated upper and lower limits, e.g., about 30° C. to about300° C., about 50° C. to about 250° C., about 60° C. to about 200° C.,about 75° C. to about 125° C., about 150° C. to about 250° C., bout 175°C. to about 225° C., etc. In particular, the second temperature is about50° C. to about 250° C., about 75° C. to about 125° C. or about 175° C.to about 225° C.

The second pressure in combination with above described secondtemperature may be such that the partial pressure of CO₂ is ≥about 0.01bar, ≥about 0.02 bar, ≥about 0.03 bar, ≥about 0.04 bar, ≥about 0.05 bar,≥about 0.06 bar, ≥about 0.07 bar, ≥about 0.08 bar, ≥about 0.09 bar,≥about 0.1 bar, ≥about 0.2 bar, ≥about 0.3 bar, ≥about 0.4 bar, ≥about0.5 bar, ≥about 0.6 bar, ≥about 0.7 bar, ≥about 0.8 bar, ≥about 0.9 bar,≥about 0.95 bar or about 0.99 bar. In particular, the second pressuremay be such that the partial pressure of CO₂ is ≥about 0.1 bar or ≥about0.2 bar. Additionally or alternatively, the second pressure may be suchthat the partial pressure of CO₂ is ≤about 0.01 bar, ≤about 0.02 bar,≤about 0.03 bar, ≤about 0.04 bar, ≤about 0.05 bar, ≤about 0.06 bar,≤about 0.07 bar, ≤about 0.08 bar, ≤about 0.09 bar, ≤about 0.1 bar,≤about 0.2 bar, ≤about 0.3 bar, ≤about 0.4 bar, ≤about 0.5 bar, ≤about0.6 bar, ≤about 0.7 bar, ≤about 0.8 bar, ≤about 0.9 bar, ≤about 0.95 baror ≤0.99 bar. Ranges expressly disclosed include combinations of theabove-enumerated upper and lower limits, e.g., about 0.01 bar to about0.99 bar, about 0.05 bar to about 0.8 bar, about 0.05 bar to about 0.5bar, about 0.07 bar to about 0.4 bar, about 0.09 bar to about 0.4 bar,about 0.08 bar to about 0.3 bar, etc. In particular, the second pressuremay be such that the partial pressure of CO₂ is about 0.05 bar to about0.5 bar, about 0.09 bar to about 0.4 bar or about 0.08 bar to about 0.3bar.

In various aspects, the adsorbent material may comprise a zeolite havinga Si/Al ratio above about 100 (e.g. above about 200, above about 400,above about 600, etc.) and a CAS framework structure. Additionally oralternatively, these zeolites may include a cation concentration of lessthan about 10%, less than about 5%, less than about 1%, less than about0.1%, or about 0%.

Additionally or alternatively, the adsorbent material may comprise azeolite with a framework structure selected from the group consisting ofAFT, AFX, CAS, DAC, EMT, EUO, HEU, IMF, IRR, IRY, ITH, ITT, KFI, LAU,MFS, MRE, MTT, MWW, NES, PAU, RRO, RWY, SFF, STF, STI, SZR, TER, TON,TSC, TUN, VFI, and a combination thereof, having (i) a Si/Al ratio ofabout 1 to about 100, about 1 to 90, about 1 to about 75, about 1 toabout 50, about 1 to about 25, or about 1 to about 10; and/or (ii) acation concentration (e.g., potassium cation, sodium cation) of about 0%to about 100%, about 0% to about 90%, about 0% to about 50%, about 0% toabout 40%, or about 0% to about 30%.

Additionally or alternatively, the adsorbent material may comprise azeolite with a framework structure selected from the group consisting ofAFT, AFX, KFI, PAU, TSC, and a combination thereof, having (i) a Si/Alratio of about 1 to about 30, about 1 to about 20, or about 1 to about10; and/or a (ii) a cation concentration (e.g., potassium cation, sodiumcation) of about 0% to about 50%, about 0% to about 40%, or about 0% toabout 20%.

Additionally or alternatively, the above mentioned adsorbent materialsmay not include a zeolite with a framework structure selected from thegroup consisting of CHA, FAU, LTA, RHO and a combination thereof.

Additionally or alternatively, the adsorbent material may comprise azeolite with a framework structure selected from the group consisting ofCHA, FAU, FER, MFI, RHO, UFI, and a combination thereof, having (i) aSi/Al ratio of between about 1 and about 30, about 1 to about 20, orabout 1 to about 10; and/or (ii) a cation concentration (e.g., potassiumcation, sodium cation) of about 0% to about 40%, about 0% to about 20%,about 0% to about 10%, or about 0% to about 5%.

Additionally or alternatively, the adsorbent material may comprise azeolite with a LTA framework structure having (i) a Si/Al ratio ofbetween about 1 and about 20, about 1 to about 10, or about 1 to about5; and/or (ii) a cation concentration (e.g., potassium cation, sodiumcation) of about 0% to about 40%, about 2% to about 40%, about 5% toabout 40%, about 5% to about 20%, or about 5% to about 10%.

Additionally or alternatively, the adsorbent material may comprise azeolite with a framework structure selected from the group consisting ofCHA, FAU, RHO, and a combination thereof, having (i) a Si/Al ratio ofbetween about 1 and about 30, about 1 to about 20, or about 1 to about10; and/or (ii) a cation concentration (e.g., potassium cation, sodiumcation) of about 0% to about 40%, about 0% to about 20%, about 0% toabout 10%, or about 0% to about 5%.

Additionally or alternatively, the adsorbent material may have a workingcapacity of ≥about 1.0 mmol/cc, ≥about 2.0 mmol/cc, ≥about 3.0 mmol/cc,≥about 4.0 mmol/cc, ≥about 5.0 mmol/cc, ≥about 6.0 mmol/cc, ≥about 7.0mmol/cc, ≥about 8.0 mmol/cc, ≥about 9.0 mmol/cc, ≥about 10.0 mmol/cc,≥about 11.0 mmol/cc, ≥about 12.0 mmol/cc, ≥about 13.0 mmol/cc, ≥about14.0 mmol/cc, ≥about 15.0 mmol/cc, ≥about 16.0 mmol/cc, ≥about 17.0mmol/cc, ≥about 18.0 mmol/cc, ≥about 19.0 mmol/cc, or ≥about 20.0mmol/cc. Additionally or alternatively, the adsorbent material describedherein may have a working capacity of ≤about 1.0 mmol/cc, ≤about 2.0mmol/cc, ≤about 3.0 mmol/cc, ≤about 4.0 mmol/cc, ≤about 5.0 mmol/cc,≤about 6.0 mmol/cc, ≤about 7.0 mmol/cc, ≤about 8.0 mmol/cc, ≤about 9.0mmol/cc, ≤about 10.0 mmol/cc, ≤about 11.0 mmol/cc, ≤about 12.0 mmol/cc,≤about 13.0 mmol/cc, ≤about 14.0 mmol/cc, ≤about 15.0 mmol/cc, ≤about16.0 mmol/cc, ≤about 17.0 mmol/cc, ≤about 18.0 mmol/cc, ≤about 19.0mmol/cc, or ≤about 20.0 mmol/cc. Ranges expressly disclosed includecombinations of the above-enumerated values, e.g., about 1.0 mmol/cc toabout 20.0 mmol/cc, about 1.0 mmol/cc to about 16.0 mmol/cc, about 2.0mmol/cc to about 15.0 mmol/cc, about 3.0 mmol/cc to about 14.0 mmol/cc,about 5.0 mmol/cc to about 12.0 mmol/cc, etc. In particular, theadsorbent material described herein may have a working capacity of about3.0 mmol/cc to about 14.0 mmol/cc or about 5.0 mmol/cc to about 12.0mmol/cc.

Additionally or alternatively, the adsorbent material may have anaverage heat of adsorption of ≥about 15 kJ/mol, ≥about 16 kJ/mol, ≥about18 kJ/mol, ≥about 20 kJ/mol, ≥about 22 kJ/mol, ≥about 24 kJ/mol, ≥about25 kJ/mol, ≥about 26 kJ/mol, ≥about 28 kJ/mol, ≥about 30 kJ/mol, ≥about32 kJ/mol, ≥about 34 kJ/mol, ≥about 35 kJ/mol, ≥about 36 kJ/mol, ≥about38 kJ/mol, ≥about 40 kJ/mol, ≥about 42 kJ/mol, ≥about 44 kJ/mol, ≥about45 kJ/mol, ≥about 46 kJ/mol, ≥about 48 kJ/mol, ≥about 50 kJ/mol, ≥about52 kJ/mol, ≥about 54 kJ/mol, ≥about 55 kJ/mol, ≥about 56 kJ/mol, ≥about58 kJ/mol, or ≥about 60 kJ/mol. Additionally or alternatively, theadsorbent material may have an average heat of adsorption of ≤about 15kJ/mol, ≤about 16 kJ/mol, ≤about 18 kJ/mol, ≤about 20 kJ/mol, ≤about 22kJ/mol, ≤about 24 kJ/mol, ≤about 25 kJ/mol, ≤about 26 kJ/mol, ≤about 28kJ/mol, ≤about 30 kJ/mol, ≤about 32 kJ/mol, ≤about 34 kJ/mol, ≤about 35kJ/mol, ≤about 36 kJ/mol, ≤about 38 kJ/mol, ≤about 40 kJ/mol, ≤about 42kJ/mol, ≤about 44 kJ/mol, ≤about 45 kJ/mol, ≤about 46 kJ/mol, ≤about 48kJ/mol, ≤about 50 kJ/mol, ≤about 52 kJ/mol, ≤about 54 kJ/mol, ≤about 55kJ/mol, ≤about 56 kJ/mol, ≤about 58 kJ/mol, or ≤about 60 kJ/mol. Rangesexpressly disclosed include combinations of the above-enumerated values,e.g., about 15 kJ/mol to about 60 kJ/mol, about 25 kJ/mol to about 58kJ/mol, about 28 kJ/mol to about 54 kJ/mol, about 30 kJ/mol to about 55kJ/mol, etc. In particular, the adsorbent material for use in the VTSAprocess described herein may have an average heat of adsorption of about25 kJ/mol to about 58 kJ/mol, about 28 kJ/mol to about 54 kJ/mol orabout 30 kJ/mol to about 55 kJ/mol.

In various aspects, an adsorbent material comprising one or more of thefollowing: (i) a zeolite having a Si/Al ratio above about 100 with a CASframework structure; or (ii) a zeolite with a framework structureselected from the group consisting of AFT, AFX, CAS, DAC, EMT, EUO, HEU,IMF, IRR, IRY, ITH, ITT, KFI, LAU, MFS, MRE, MTT, MWW, NES, PAU, RRO,RWY, SFF, STF, STI, SZR, TER, TON, TSC, TUN, VFI, and a combinationthereof, having: (a) a Si/Al ratio of about 1 to about 100; and/or (b) apotassium cation concentration of about 0% to about 100%, for use in aVTSA process for separating CO₂ from a feed gas mixture is provided.

In various aspects, an adsorbent material comprising one or more of thefollowing: (i) a zeolite with a framework structure selected from thegroup consisting of CHA, FAU, FER, MFI, RHO, UFI and a combinationthereof, having: (a) a Si/Al ratio of about 1 to about 20; and/or (b) apotassium cation concentration of about 0% to about 40%; or (ii) azeolite with a LTA framework structure having: (a) a Si/Al ratio ofabout 1 to about 20; and/or (b) a potassium cation concentration ofabout 5% to about 40%, for use in a VTSA process for separating CO₂ froma feed gas mixture is provided.

Nonlimiting examples of suitable zeolites for use in the VTSA describedherein are those which are provided below in Table 9.

TABLE 9 Zeolites AFT_3_0 MFI_10_33 AFT_5_0 MFS_10_17 AFX_3_0 MRE_2_0AFX_10_17 MTT_10_83 CAS_20 MWW_2_0 CAS_Si MWW_2_33 CHA_10_0 NES_2_0CHA_1_0 PAU_5_0 DAC_50_17 PAU_10_33 EMT_1_0 RHO_3_0 EMT_2_0 RHO_5_0EUO_3_0 RRO_10_83 FAU_1_0 RWY_3_17 FAU_2_33 SFF_2_0 FER_10_33 SFF_3_0HEU_25_17 STF_2_0 IMF_10_0 STF_5_0 IRR_2_0 STI_2_0 IRY_2_0 SZR_5_67ITH_10_17 TER_10_17 ITT_2_0 TON_25_0 ITT_2_17 TSC_1_0 KFI_3_0 TUN_10_67LAU_10_0 UFI_2_0 LTA_1_0 VFI_2_0 KFI_5_0

E. Temperature Swing Adsorption (TSA) Processes

In another embodiment, a TSA process for separating CO₂ from a feed gasmixture is provided. The TSA process may include subjecting the feed gasmixture comprising CO₂ to an adsorption step by introducing the feed gasmixture into a feed input end of an adsorbent bed. The feed gas mixturemay be natural gas, syngas, flue gas as well as other streams containingCO₂. Typical natural gas mixtures contain CH₄ and higher hydrocarbons(C₂H₆, C₃H₈, C₄H₁₀ etc), as well as acid gases (CO₂ and H₂₅), N₂ andH₂O. The amount of water in the natural gas mixture depends on priordehydration processing to remove H₂O. Typical syngas mixtures containH₂, CO, CO₂, CH₄, COS and H₂S. Typical flue gas mixtures contain N₂,CO₂, H₂O, O₂, SO₂. The adsorbent bed may comprise a feed input end, aproduct output end and an adsorbent material selective for adsorbingCO₂. Additionally, the adsorbent bed may be operated at a first pressureand at a first temperature wherein at least a portion of the CO₂ in thefeed gas mixture is adsorbed by the adsorbent bed and wherein a gaseousproduct depleted in CO₂ exits the product output end of the adsorbentbed.

The first temperature may be ≥about −30° C., ≥about −25° C., ≥about −20°C., ≥about-15° C., ≥about −10° C., ≥about −5° C., ≥about 0° C., ≥about5° C., ≥about 10° C., ≥about 15° C., ≥about 20° C., ≥about 25° C.,≥about 30° C., ≥about 35° C., ≥about 40° C., ≥about 45° C., ≥about 50°C., ≥about 55° C., ≥about 60° C., ≥about 65° C., ≥about 70° C., ≥about75° C., ≥about 80° C., ≥about 85° C., ≥about 90° C., ≥about 95° C., or≥about 100° C. In particular, the first temperature may be ≥about 25° C.Additionally or alternatively, the first temperature may be ≤about −30°C., ≤about −25° C., ≤about −20° C., ≤about −15° C., ≤about −10° C.,≤about −5° C., ≤about 0° C., ≤about 5° C., ≤about 10° C., ≤about 15° C.,≤about 20° C., ≤about 25° C., ≤about 30° C., ≤about 35° C., ≤about 40°C., ≤about 45° C., ≤about 50° C., ≤about 55° C., ≤about 60° C., ≤about65° C., ≤about 70° C., ≤about 75° C., ≤about 80° C., ≤about 85° C.,≤about 90° C., ≤about 95° C., or ≤about 100° C. Ranges expresslydisclosed include combinations of the above-enumerated upper and lowerlimits, e.g., about −30° C. to about 100° C., about −25° C. to about 95°C., about −20° C. to about 80° C., about 0° C. to about 50° C., about10° C. to about 30° C. In particular, the first temperature is about-20°C. to about 80° C., about 0° C. to about 50° C. or about 10° C. to about30° C.

The first pressure in combination with the above described firsttemperatures may be such that the partial pressure of CO₂ may be ≥about0.1 bar, ≥about 0.2 bar, ≥about 0.3 bar, ≥about 0.4 bar, ≥about 0.5 bar,≥about 0.6 bar, ≥about 0.7 bar, ≥about 0.8 bar, ≥about 0.9 bar, ≥about 1bar, ≥about 2 bar, ≥about 3 bar, ≥about 4 bar, ≥about 6 bar, ≥about 7bar, ≥about 8 bar, ≥about 9 bar, or ≥about 10 bar. In particular, thefirst pressure in combination with the above described firsttemperatures may be such that the partial pressure of CO₂ is ≥about 1bar. Additionally or alternatively, the first pressure in combinationwith above described first temperature may be such that the partialpressure of CO₂ is ≤about 0.1 bar, ≤about 0.2 bar, ≤about 0.3 bar,≤about 0.4 bar, ≤about 0.5 bar, ≤about 0.6 bar, ≤about 0.7 bar, ≤about0.8 bar, ≤about 0.9 bar, ≤about 1 bar, ≤about 2 bar, ≤about 3 bar,≤about 4 bar, ≤about 6 bar, ≤about 7 bar, ≤about 8 bar, ≤about 9 bar, or≤about 10 bar. Ranges expressly disclosed include combinations of theabove-enumerated upper and lower limits, e.g., about 0.1 bar to about 10bar, about 0.3 bar to about 9 bar, about 0.5 bar to about 5 bar, about0.5 bar to about 3 bar, about 1 bar to about 5 bar, etc. In particular,the first pressure in combination with above described first temperaturemay be such that the partial pressure of CO₂ is about 0.5 bar to about 3bar, about 0.5 bar to about 6 bar, about 1 bar to about 5 bar, or about0.7 bar to about 2 bar.

In various aspects, the TSA process may further include stopping theintroduction of the feed gas mixture to the adsorbent bed beforebreakthrough of CO₂ from the product output end of the adsorbent bed andheating the adsorbent bed to a second temperature higher than the firsttemperature, resulting in desorption of at least a portion of CO₂ fromthe adsorbent bed and recovering at least a portion of CO₂ from theadsorbent bed. The second temperature may be ≥about 30° C., ≥about 35°C., ≥about 40° C., ≥about 45° C., ≥about 50° C., ≥about 55° C., ≥about60° C., ≥about 65° C., ≥about 70° C., ≥about 75° C., ≥about 80° C.,≥about 85° C., ≥about 90° C., ≥about 95° C., ≥about 100° C., ≥about 105°C., ≥about 110° C., ≥about 115° C., ≥about 120° C., ≥about 125° C.,≥about 130° C., ≥about 135° C., ≥about 140° C., ≥about 145° C., ≥about150° C., ≥about 155° C., ≥about 160° C., ≥about 165° C., ≥about 170° C.,≥about 175° C., ≥about 180° C., ≥about 185° C., ≥about 190° C., ≥about195° C., ≥about 200° C., ≥about 205° C., ≥about 210° C., ≥about 215° C.,≥about 220° C., ≥about 225° C., ≥about 250° C., ≥about 275° C., or ≥300°C. In particular, the second temperature may be ≥about 95° C. or ≥about195° C. Additionally or alternatively, the second temperature may be≤about 30° C., ≤about 35° C., ≤about 40° C., ≤about 45° C., ≤about 50°C., ≤about 55° C., ≤about 60° C., ≤about 65° C., ≤about 70° C., ≤about75° C., ≤about 80° C., ≤about 85° C., ≤about 90° C., ≤about 95° C.,≤about 100° C., ≤about 105° C., ≤about 110° C., ≤about 115° C., ≤about120° C., ≤about 125° C., ≤about 130° C., ≤about 135° C., ≤about 140° C.,≤about 145° C., ≤about 150° C., ≤about 155° C., ≤about 160° C., ≤about165° C., ≤about 170° C., ≤about 175° C., ≤about 180° C., ≤about 185° C.,≤about 190° C., ≤about 195° C., ≤about 200° C., ≤about 205° C., ≤about210° C., ≤about 215° C., ≤about 220° C., ≤about 225° C., ≤about 250° C.,≤about 275° C., or ≤300° C. Ranges expressly disclosed includecombinations of the above-enumerated upper and lower limits, e.g., about30° C. to about 300° C., about 50° C. to about 250° C., about 60° C. toabout 200° C., about 75° C. to about 125° C., about 150° C. to about250° C., about 175° C. to about 225° C., etc. In particular, the secondtemperature is about 50° C. to about 250° C., about 150° C. to about250° C., about 75° C. to about 125° C. or about 175° C. to about 225° C.

In various aspects, the adsorbent material may comprise a zeolite havinga Si/Al ratio above about 100 (e.g. above about 200, above about 400,above about 600, etc.) and a CAS framework structure. Additionally oralternatively, these zeolites may include a cation concentration of lessthan about 10%, less than about 5%, less than about 1%, less than about0.1%, or about 0%.

Additionally or alternatively, the adsorbent material may comprise azeolite with a framework structure selected from the group consisting ofAFT, AFX, CAS, EMT, IRR, IRY, ITT, KFI, MWW, PAU, RWY, SFF, STF, TSC,UFI, VFI, and a combination thereof, having (i) a Si/Al ratio of about 1to about 50, about 1 to 20, about 1 to about 10, or about 1 to about 5;and/or (ii) a cation concentration (e.g., potassium cation, sodiumcation) of about 0% to about 50%, about 0% to about 40%, about 0% toabout 30%, or about 0% to about 20%.

Additionally or alternatively, the adsorbent material may comprise azeolite with a framework structure selected from the group consisting ofAFT, AFX, KFI, PAU, TSC, UFI, and a combination thereof, having (i) aSi/Al ratio of about 1 to about 50, about 1 to 20, about 1 to about 10,or about 1 to about 5; and/or (ii) a cation concentration (e.g.,potassium cation, sodium cation) of about 0% to about 50%, about 0% toabout 40%, about 0% to about 30%, or about 0% to about 20%.

Additionally or alternatively, the above mentioned adsorbent materialsmay not include a zeolite with a framework structure selected from thegroup consisting of CHA, FAU, LTA, RHO and a combination thereof.

Additionally or alternatively, the adsorbent material may comprise azeolite with a framework structure selected from the group consisting ofCHA, FAU, FER, MFI, RHO, UFI, and a combination thereof, having (i) aSi/Al ratio of between about 1 and about 30, about 1 to about 20, about1 to about 10 or about 1 to about 5; and/or (ii) a cation concentration(e.g., potassium cation, sodium cation) of about 0% to about 40%, about0% to about 20%, about 0% to about 10%, or about 0% to about 5%.

Additionally or alternatively, the adsorbent material may comprise azeolite with a LTA framework structure having (i) a Si/Al ratio ofbetween about 1 and about 20, about 1 to about 10, or about 1 to about5; and/or (ii) a cation concentration (e.g., potassium cation, sodiumcation) of about 0% to about 40%, about 2% to about 40%, about 5% toabout 40%, about 5% to about 20%, or about 5% to about 10%.

Additionally or alternatively, the adsorbent material may comprise azeolite with a framework structure selected from the group consisting ofCHA, FAU, RHO and a combination thereof, having (i) a Si/Al ratio ofbetween about 1 and about 30, about 1 to about 20, about 1 to about 10or about 1 to about 5; and/or (ii) a cation concentration (e.g.,potassium cation, sodium cation) of about 0% to about 40%, about 0% toabout 20%, about 0% to about 10%, or about 0% to about 5%.

Additionally or alternatively, the adsorbent material may have a workingcapacity of ≥about 1.0 mmol/cc, ≥about 2.0 mmol/cc, ≥about 3.0 mmol/cc,≥about 4.0 mmol/cc, ≥about 5.0 mmol/cc, ≥about 6.0 mmol/cc, ≥about 7.0mmol/cc, ≥about 8.0 mmol/cc, ≥about 9.0 mmol/cc, ≥about 10.0 mmol/cc,≥about 11.0 mmol/cc, ≥about 12.0 mmol/cc, ≥about 13.0 mmol/cc, ≥about14.0 mmol/cc, ≥about 15.0 mmol/cc, ≥about 16.0 mmol/cc, ≥about 17.0mmol/cc, ≥about 18.0 mmol/cc, ≥about 19.0 mmol/cc, or ≥about 20.0mmol/cc. Additionally or alternatively, the adsorbent material describedherein may have a working capacity of ≤about 1.0 mmol/cc, ≤about 2.0mmol/cc, ≤about 3.0 mmol/cc, ≤about 4.0 mmol/cc, ≤about 5.0 mmol/cc,≤about 6.0 mmol/cc, ≤about 7.0 mmol/cc, ≤about 8.0 mmol/cc, ≤about 9.0mmol/cc, ≤about 10.0 mmol/cc, ≤about 11.0 mmol/cc, ≤about 12.0 mmol/cc,≤about 13.0 mmol/cc, ≤about 14.0 mmol/cc, ≤about 15.0 mmol/cc, ≤about16.0 mmol/cc, ≤about 17.0 mmol/cc, ≤about 18.0 mmol/cc, ≤about 19.0mmol/cc, or ≤about 20.0 mmol/cc. Ranges expressly disclosed includecombinations of the above-enumerated values, e.g., about 1.0 mmol/cc toabout 20.0 mmol/cc, about 1.0 mmol/cc to about 16.0 mmol/cc, about 2.0mmol/cc to about 15.0 mmol/cc, about 3.0 mmol/cc to about 14.0 mmol/cc,about 3.0 mmol/cc to about 12.0 mmol/cc, about 5.0 mmol/cc to about 10.0mmol/cc, etc. In particular, the adsorbent material described herein mayhave a working capacity of about 3.0 mmol/cc to about 12.0 mmol/cc orabout 5.0 mmol/cc to about 10.0 mmol/cc.

Additionally or alternatively, the adsorbent material for use in the TSAprocess described herein may have an average heat of adsorption of≥about 15 kJ/mol, ≥about 16 kJ/mol, ≥about 18 kJ/mol, ≥about 20 kJ/mol,≥about 22 kJ/mol, ≥about 24 kJ/mol, ≥about 25 kJ/mol, ≥about 26 kJ/mol,≥about 28 kJ/mol, ≥about 30 kJ/mol, ≥about 32 kJ/mol, ≥about 34 kJ/mol,≥about 35 kJ/mol, ≥about 36 kJ/mol, ≥about 38 kJ/mol, ≥about 40 kJ/mol,≥about 42 kJ/mol, ≥about 44 kJ/mol, ≥about 45 kJ/mol, ≥about 46 kJ/mol,≥about 48 kJ/mol, ≥about 50 kJ/mol, ≥about 52 kJ/mol, ≥about 54 kJ/mol,≥about 55 kJ/mol, ≥about 56 kJ/mol, ≥about 58 kJ/mol, or ≥about 60kJ/mol. Additionally or alternatively, the adsorbent material for use inthe TSA process described herein may have an average heat of adsorptionof ≤about 15 kJ/mol, ≤about 16 kJ/mol, ≤about 18 kJ/mol, ≤about 20kJ/mol, ≤about 22 kJ/mol, ≤about 24 kJ/mol, ≤about 25 kJ/mol, ≤about 26kJ/mol, ≤about 28 kJ/mol, ≤about 30 kJ/mol, ≤about 32 kJ/mol, ≤about 34kJ/mol, ≤about 35 kJ/mol, ≤about 36 kJ/mol, ≤about 38 kJ/mol, ≤about 40kJ/mol, ≤about 42 kJ/mol, ≤about 44 kJ/mol, ≤about 45 kJ/mol, ≤about 46kJ/mol, ≤about 48 kJ/mol, ≤about 50 kJ/mol, ≤about 52 kJ/mol, ≤about 54kJ/mol, ≤about 55 kJ/mol, ≤about 56 kJ/mol, ≤about 58 kJ/mol, or ≤about60 kJ/mol. Ranges expressly disclosed include combinations of theabove-enumerated values, e.g., about 15 kJ/mol to about 60 kJ/mol, about25 kJ/mol to about 58 kJ/mol, about 28 kJ/mol to about 54 kJ/mol, about28 kJ/mol to about 52 kJ/mol, etc. In particular, the adsorbent materialfor use in the TSA process described herein may have an average heat ofadsorption of about 25 kJ/mol to about 58 kJ/mol, about 28 kJ/mol toabout 54 kJ/mol or about 28 kJ/mol to about 52 kJ/mol.

In various aspects, an adsorbent material comprising a zeolite with aframework structure selected from the group consisting of AFT AFX, CAS,EMT, IRR, IRY, ITT, KFI, MWW, PAU, RWY, SFF, STF, TSC, UFI, VFI, and acombination thereof, having: (a) a Si/Al ratio of about 1 to about 20;and/or (b) a potassium cation concentration of about 0% to about 50%,for use in a TSA process for separating CO₂ from a feed gas mixture isprovided.

In various aspects, an adsorbent material comprising one or more of thefollowing: (i) a zeolite with a framework structure selected from thegroup consisting of CHA, FAU, RHO, and a combination thereof, having:(a) a Si/Al ratio of about 1 to about 20; and (b) a potassium cationconcentration of about 0% to about 40%; or (ii) a zeolite with a LTAframework structure having: (a) a Si/Al ratio of about 1 to about 20;and/or (b) a potassium cation concentration of about 5% to about 40%,for use in a TSA process for separating CO₂ from a feed gas mixture isprovided.

Nonlimiting examples of suitable zeolites for use in the TSA describedherein are those which are provided below in Table 10.

TABLE 10 Zeolites IRY_2_0 IRR_2_0 FAU_1_0 EMT_1_0 ITT_2_0 RHO_5_0KFI_3_0 RWY_3_17 PAU_5_33 TSC_1_0 CHA_1_0 UFI_2_ 0 LTA_1_0 AFX_3_0AFT_3_0 SFF_2_0 STF_5_0 MWW_3_0 VFI_2_0 CAS_2_0

Adsorptive kinetic separation processes, apparatuses, and systems, asdescribed above, are useful for development and production ofhydrocarbons, such as gas and oil processing. Particularly, the providedprocesses, apparatuses, and systems can be useful for the rapid, largescale, efficient separation of a variety of target gases from gasmixtures.

The provided processes, apparatuses, and systems may be used to preparenatural gas products by removing contaminants. The provided processes,apparatuses, and systems can be useful for preparing gaseous feedstreams for use in utilities, including separation applications such asdew point control, sweetening/detoxification, corrosionprotection/control, dehydration, heating value, conditioning, andpurification. Examples of utilities that utilize one or more separationapplications can include generation of fuel gas, seal gas, non-potablewater, blanket gas, instrument and control gas, refrigerant, inert gas,and hydrocarbon recovery. Exemplary “not to exceed” product (or“target”) acid gas removal specifications can include: (a) 2 vol % CO₂,4 ppm H₂S; (b) 50 ppm CO₂, 4 ppm H₂S; or (c) 1.5 vol % CO₂, 2 ppm H₂S.

The provided processes, apparatuses, and systems may be used to removeacid gas from hydrocarbon streams. Acid gas removal technology becomesincreasingly important as remaining gas reserves exhibit higherconcentrations of acid (sour) gas resources. Hydrocarbon feed streamscan vary widely in amount of acid gas, such as from several parts permillion to 90 vol %. Non-limiting examples of acid gas concentrationsfrom exemplary gas reserves can include concentrations of at least: (a)1 vol % H₂S, 5 vol % CO₂; (b) 1 vol % H₂S, 15 vol % CO₂; (c) 1 vol %H₂S, 60 vol % CO₂; (d) 15 vol % H₂S, 15 vol % CO₂; or (e) 15 vol % H₂S,30 vol % CO₂.

One or more of the following may be utilized with the processes,apparatuses, and systems provided herein, to prepare a desirable productstream, while maintaining relatively high hydrocarbon recovery:

(a) using one or more kinetic swing adsorption processes, such aspressure swing adsorption (PSA), temperature swing adsorption (TSA), andvacuum swing adsorption (VSA), including combinations of theseprocesses; each swing adsorption process may be utilized with rapidcycles, such as using one or more rapid cycle pressure swing adsorption(RC-PDS) units, with one or more rapid cycle temperature swingadsorption (RC-TSA) units; exemplary kinetic swing adsorption processesare described in U.S. Patent Application Publication Nos. 2008/0282892,2008/0282887, 2008/0282886, 2008/0282885, and 2008/0282884, which areeach herein incorporated by reference in its entirety;

(b) removing acid gas with RC-TSA using advanced cycles and purges asdescribed in U.S. Provisional Application No. 61/447,858, filed 1 Mar.2011, as well as the U.S. patent application Ser. No. 13/406,079,claiming priority thereto, which are together incorporated by referenceherein in their entirety;

(c) using a mesopore filler to reduce the amount of trapped methane inthe adsorbent and increase the overall hydrocarbon recovery, asdescribed in U.S. Patent Application Publication Nos. 2008/0282892,2008/0282885, and 2008/028286, each of which is herein incorporated byreference in its entirety;

(d) depressurizing one or more RC-TSA units in multiple steps tointermediate pressures so that the acid gas exhaust can be captured at ahigher average pressure, thereby decreasing the compression required foracid gas injection; pressure levels for the intermediatedepressurization steps may be matched to the interstage pressures of theacid gas compressor to optimize the overall compression system;

(e) using exhaust or recycle streams to minimize processing andhydrocarbon losses, such as using exhaust streams from one or moreRC-TSA units as fuel gas instead of re-injecting or venting;

(f) using multiple adsorbent materials in a single bed to remove traceamounts of first contaminants, such as H₂S, before removal of a secondcontaminant, such as CO₂; such segmented beds may provide rigorous acidgas removal down to ppm levels with RC-TSA units with minimal purge flowrates;

(g) using feed compression before one or more RC-TSA units to achieve adesired product purity;

(h) contemporaneous removal of non-acid gas contaminants such asmercaptans, COS, and BTEX; selection processes and materials toaccomplish the same;

(i) using structured adsorbents for gas-solid contactors to minimizepressure drop compared to conventional packed beds;

(j) selecting a cycle time and cycle steps based on adsorbent materialkinetics; and

(k) using a process and apparatus that uses, among other equipment, twoRC-TSA units in series, wherein the first RC-TSA unit cleans a feedstream down to a desired product purity and the second RC-TSA unitcleans the exhaust from the first unit to capture methane and maintainhigh hydrocarbon recovery; use of this series design may reduce the needfor a mesopore filler.

The processes, apparatuses, and systems provided herein can be useful inlarge gas treating facilities, such as facilities that process more thanfive million standard cubic feet per day (MSCFD) of natural gas, forexample more than 15 MSCFD, more than 25 MSCFD, more than 50 MSCFD, morethan 100 MSCFD, more than 500 MSCFD, more than one billion standardcubic feet per day (BSCFD), or more than two BSCFD.

FURTHER EMBODIMENTS

The invention can additionally or alternatively include one or more ofthe following embodiments.

Embodiment 1

A pressure swing adsorption process for separating CO₂ from a feed gasmixture (e.g., natural gas stream), wherein the process comprises: a)subjecting the feed gas mixture comprising CO₂ to an adsorption step byintroducing the feed gas mixture into a feed input end of an adsorbentbed, wherein the adsorbent bed comprises: a feed input end and a productoutput end; and an adsorbent material selective for adsorbing CO₂,wherein the adsorbent material comprises one or more of the following:(i) a zeolite having a Si/Al ratio above about 100 and a frameworkstructure selected from the group consisting of AFT, AFX, DAC, EMT, EUO,IMF, ITH, ITT, KFI, LAU, MFS, MRE, MTT, MWW, NES, PAU, RRO, SFF, STF,STI, SZR, TER, TON, TSC, TUN, VFI, and a combination thereof; or (ii) azeolite with a framework structure selected from the group consisting ofCAS, EMT, FAU, HEU, IRR, IRY, ITT, LTA, RWY, TSC and VFI, and acombination thereof, having: (a) a Si/Al ratio of about 5 to about 85 orabout 5 to about 70; and/or (b) a potassium cation concentration ofabout 5% to about 100% or about 10% to about 100%; wherein the adsorbentbed is operated at a first pressure (e.g., such that the partialpressure of CO₂ is from about 3 bar to about 25 bar, about 3 bar toabout 10 bar, about 15 bar to about 25 bar) and at a first temperature(e.g., about −20° C. to about 80° C., about 0° C. to about 50° C.)wherein at least a portion of the CO₂ in the feed gas mixture isadsorbed by the adsorbent bed and wherein a gaseous product depleted inCO₂ exits the product output end of the adsorbent bed; b) stopping theintroduction of the feed gas mixture to the adsorbent bed beforebreakthrough of CO₂ from the product output end of the adsorbent bed; c)reducing the pressure in the adsorption bed to a second pressure (e.g.,such that the partial pressure of CO₂ is from about 0.5 bar to about 2bar) resulting in desorption of at least a portion of CO₂ from theadsorbent bed; and d) recovering at least a portion of CO₂ from theadsorbent bed.

Embodiment 2

The process of embodiment 1, wherein the adsorbent material comprisesone or more of the following: (i) a zeolite having a Si/Al ratio aboveabout 100 and a framework structure selected from the group consistingof AFT, AFX, KFI, PAU, TSC, and a combination thereof; or (ii) a zeolitewith a framework structure selected from the group consisting of LTA,TSC, and a combination thereof, having: (a) a Si/Al ratio of about 40 toabout 60; and/or (b) a potassium cation concentration of about 50% toabout 90%.

Embodiment 3

A pressure swing adsorption process for separating CO₂ from a feed gasmixture (e.g., natural gas stream), wherein the process comprises: a)subjecting the feed gas mixture comprising CO₂ to an adsorption step byintroducing the feed gas mixture into a feed input end of an adsorbentbed, wherein the adsorbent bed comprises: a feed input end and a productoutput end; and an adsorbent material selective for adsorbing CO₂,wherein the adsorbent material comprises a zeolite having a Si/Al ratioof between about 5 and about 45 and with a framework structure selectedfrom the group consisting of CHA, FAU, FER, LTA, MFI, RHO, UFI, and acombination thereof; wherein the adsorbent bed is operated at a firstpressure (e.g., such that the partial pressure of CO₂ is from about 3bar to about 25 bar, about 3 bar to about 10 bar, about 15 bar to about25 bar) and at a first temperature (e.g., about −20° C. to about 80° C.,about 0° C. to about 50° C.) wherein at least a portion of the CO₂ inthe feed gas mixture is adsorbed by the adsorbent bed and wherein agaseous product depleted in CO₂ exits the product output end of theadsorbent bed; b) stopping the introduction of the feed gas mixture tothe adsorbent bed before breakthrough of CO₂ from the product output endof the adsorbent bed; c) reducing the pressure in the adsorption bed toa second pressure (e.g., such that the partial pressure of CO₂ is fromabout 0.5 bar to about 2 bar) resulting in desorption of at least aportion of CO₂ from the adsorbent bed; and d) recovering at least aportion of CO₂ from the adsorbent bed.

Embodiment 4

The process of any one of the previous embodiments, wherein theadsorbent material has a working capacity of about 2.0 mmol/cc to about15.0 mmol/cc.

Embodiment 5

A pressure temperature swing adsorption process for separating a CO₂from a feed gas mixture (e.g., natural gas stream), wherein the processcomprises: a) subjecting the feed gas mixture comprising CO₂ to anadsorption step by introducing the feed gas mixture into a feed inputend of an adsorbent bed, wherein the adsorbent bed comprises: a feedinput end and a product output end; and an adsorbent material selectivefor adsorbing CO₂, wherein the adsorbent material comprises one or moreof the following: (i) a zeolite having a Si/Al ratio above about 100 anda framework structure selected from the group consisting of AFT, AFX,CAS, DAC, HEU, IMF, ITH, KFI, LAU, MFS, MTT, PAU, RRO, SFF, STF, SXR,TER, TON, TUN, and a combination thereof; or (ii) a zeolite with aframework structure selected from the group consisting of AFT, AFX, CHA,EMT, EUO, FAU, IRR, IRY, ITT, KFI, LTA, MRE, MWW, NES, PAU, RHO, RWY,SFF, STI, TSC, UFI, VFI, and a combination thereof, having: (a) a Si/Alratio of about 3 to about 100 or about 3 to about 75; and (b) apotassium cation concentration of about 1% to about 100%; wherein theadsorbent bed is operated at a first pressure (e.g., such that thepartial pressure of CO₂ is from about 3 bar to about 25 bar, about 3 barto about 10 bar, about 15 bar to about 25 bar) and at a firsttemperature (e.g., about −20° C. to about 80° C., from about 0° C. toabout 50° C.) wherein at least a portion of the CO₂ in the feed gasmixture is adsorbed by the adsorbent bed and wherein a gaseous productdepleted in CO₂ exits the product output end of the adsorbent bed; b)stopping the introduction of the feed gas mixture to the adsorbent bedbefore breakthrough of CO₂ from the product output end of the adsorbentbed; c) heating the adsorbent bed to a second temperature (e.g., about50° C. to about 150° C.) higher than the first temperature, resulting indesorption of at least a portion of CO₂ from the adsorbent bed andrecovering at least a first portion of CO₂; and d) reducing the pressureof the adsorbent bed to a second pressure (e.g., such that the partialpressure of CO₂ is from about 0.5 bar to about 2 bar) lower than thefirst pressure and recovering a second portion of CO₂.

Embodiment 6

The process of embodiment 5, wherein the adsorbent material comprisesone or more of the following: (i) a zeolite having a Si/Al ratio aboveabout 100 and a framework structure selected from the group consistingof AFT, AFX, KFI, PAU, TSC, and a combination thereof; or (ii) a zeolitewith a framework structure selected from the group consisting of AFT,AFX, CHA, KFI, LTA, PAU, RHO, TSC, UFI and a combination thereof,having: (a) a Si/Al ratio of about 5 to about 60; and/or (b) a potassiumcation concentration of about 1% to about 100%.

Embodiment 7

The process of embodiment 5 or 6, wherein the adsorbent material has aworking capacity of about 3.0 mmol/cc to about 17.0 mmol/cc.

Embodiment 8

A vacuum swing adsorption process for separating CO₂ from a feed gasmixture (e.g., natural gas stream), wherein the process comprises: a)subjecting the feed gas mixture comprising CO₂ to an adsorption step byintroducing the feed gas mixture into a feed input end of an adsorbentbed, wherein the adsorbent bed comprises: a feed input end and a productoutput end; and an adsorbent material selective for adsorbing CO₂,wherein the adsorbent material comprises one or more of the following;(i) a zeolite having a Si/Al ratio above about 100 and a frameworkstructure selected from the group consisting of CAS, DAC, HEU, LAU, MTT,RRO, TON, and a combination thereof; or (ii) a zeolite with a frameworkstructure selected from the group consisting of AFT, AFX, EMT, EUO, IMF,IRR, IRY, ITH, ITT, KFI, MFS, MRE, MWW, NES, PAU, RWY, SFF, STF, STI,SZR, TER, TSC, TUN, VFI, and a combination thereof, having: (a) a Si/Alratio of about 1 to about 100 or about 1 to about 75; and (b) apotassium cation concentration of about 0% to about 100%; wherein theadsorbent bed is operated at a first pressure (e.g., such that thepartial pressure of CO₂ is from about 0.5 bar to about 3 bar) and at afirst temperature (e.g., about −20° C. to about 80° C.), wherein atleast a portion of the CO₂ in the feed gas mixture is adsorbed by theadsorbent bed and wherein a gaseous product depleted in CO₂ exits theproduct output end of the adsorbent bed; b) stopping the introduction ofthe feed gas mixture to the adsorbent bed before breakthrough of CO₂from the product output end of the adsorbent bed; c) passing a purgegas, substantially free of CO₂, through the adsorbent bed therebyresulting in a reduction in the pressure in the adsorption bed to asecond pressure (e.g., such that the partial pressure of CO₂ is fromabout 0.05 bar to about 0.5 bar) and in desorption of at least a portionof CO₂ from the adsorbent bed; and d) recovering at least a portion ofCO₂ from the adsorbent bed.

Embodiment 9

The process of embodiment 8, wherein the adsorbent material comprises azeolite with a framework structure selected from the group consisting ofAFX, AFT, KFI, PAU, TSC, and a combination thereof, having: (a) a Si/Alratio of about 3 to about 60; and (b) a potassium cation concentrationof about 0% to about 100%.

Embodiment 10

A vacuum swing adsorption process for separating CO₂ from a feed gasmixture (e.g., natural gas stream), wherein the process comprises: a)subjecting the feed gas mixture comprising CO₂ to an adsorption step byintroducing the feed gas mixture into a feed input end of an adsorbentbed, wherein the adsorbent bed comprises: a feed input end and a productoutput end; and an adsorbent material selective for adsorbing CO₂,wherein the adsorbent material comprises a zeolite with a frameworkstructure selected from the group consisting of CHA, FAU, FER, LTA, MFI,RHO, UFI and a combination thereof, having (a) a Si/Al ratio of about 3to about 30; and/or (b) a potassium cation concentration of about 40% toabout 100%; wherein the adsorbent bed is operated at first pressure(e.g., such that the partial pressure of CO₂ is from about 0.5 bar toabout 3 bar) and at a first temperature (e.g., about −20° C. to about80° C.), wherein at least a portion of the CO₂ in the feed gas mixtureis adsorbed by the adsorbent bed and wherein a gaseous product depletedin CO₂ exits the product output end of the adsorbent bed; b) stoppingthe introduction of the feed gas mixture to the adsorbent bed beforebreakthrough of CO₂ from the product output end of the adsorbent bed; c)passing a purge gas, substantially free of CO₂, through the adsorbentbed thereby resulting in a reduction in the pressure in the adsorptionbed to a second pressure (e.g., such that the partial pressure of CO₂ isfrom about 0.05 bar to about 0.5 bar) and in desorption of at least aportion of CO₂ from the adsorbent bed; and d) recovering at least aportion of CO₂ from the adsorbent bed.

Embodiment 11

The process of any one of embodiments 8-10, wherein the adsorbentmaterial has a working capacity of about 3.0 mmol/cc to about 10.0mmol/cc.

Embodiment 12

A vacuum temperature swing adsorption process for separating a CO₂ froma feed gas mixture (e.g., natural gas stream), wherein the processcomprises: a) subjecting the feed gas mixture comprising CO₂ to anadsorption step by introducing the feed gas mixture into a feed inputend of an adsorbent bed, wherein the adsorbent bed comprises: a feedinput end and a product output end; and an adsorbent material selectivefor adsorbing CO₂, wherein the adsorbent material comprises one or moreof the following: (i) a zeolite having a Si/Al ratio above about 100with a CAS framework structure; or (ii) a zeolite with a frameworkstructure selected from the group consisting of AFT, AFX, CAS, DAC, EMT,EUO, HEU, IMF, IRR, IRY, ITH, ITT, KFI, LAU, MFS, MRE, MTT, MWW, NES,PAU, RRO, RWY, SFF, STF, STI, SZR, TER, TON, TSC, TUN, VFI, and acombination thereof, having: (a) a Si/Al ratio of about 1 to about 100or about 1 to about 75; and/or (b) a potassium cation concentration ofabout 0% to about 100% or about 0% to about 90%; wherein the adsorbentbed is operated at a first pressure (e.g., such that the partialpressure of CO₂ is from about 0.5 bar to about 7 bar) and at a firsttemperature (e.g., about −20° C. to about 80° C., about 0° C. to about50° C.) wherein at least a portion of the CO₂ in the feed gas mixture isadsorbed by the adsorbent bed and wherein a gaseous product depleted inCO₂ exits the product output end of the adsorbent bed; b) stopping theintroduction of the feed gas mixture to the adsorbent bed beforebreakthrough of CO₂ from the product output end of the adsorbent bed;and c) simultaneously heating the adsorbent bed to a second temperature(e.g., about 50° C. to about 250° C., about 75° C. to about 125° C.,about 175° C. to about 225° C.) higher than the first temperature andpassing a purge gas, substantially free of CO₂, through the adsorbentbed thereby resulting in a reduction in the pressure in the adsorptionbed to a second pressure (e.g., such that the partial pressure of CO₂ isfrom about 0.05 bar to about 0.5 bar, about 0.08 bar to about 0.3 bar,about 0.09 bar to about 0.4 bar), resulting in desorption of at least aportion of CO₂ from the adsorbent bed and recovering at least a portionof CO₂.

Embodiment 13

The process of embodiment 12, wherein the adsorbent material comprises azeolite with a framework structure selected from the group consisting ofAFX, AFT, KFI, PAU, TSC, and a combination thereof, having: (a) a Si/Alratio of about 1 to about 20; and/or (b) a potassium cationconcentration of about 0% to about 40%.

Embodiment 14

A vacuum temperature swing adsorption process for separating a CO₂ froma feed gas mixture (e.g., natural gas stream), wherein the processcomprises: a) subjecting the feed gas mixture comprising CO₂ to anadsorption step by introducing the feed gas mixture into a feed inputend of an adsorbent bed, wherein the adsorbent bed comprises: a feedinput end and a product output end; and an adsorbent material selectivefor adsorbing CO₂, wherein the adsorbent material comprises one or moreof the following: (i) a zeolite with a framework structure selected fromthe group consisting of CHA, FAU, FER, MFI, RHO, UFI and a combinationthereof, having: (a) a Si/Al ratio of about 1 to about 20; and/or (b) apotassium cation concentration of about 0% to about 40%; or (ii) azeolite with a LTA framework structure having: (a) a Si/Al ratio ofabout 1 to about 20; and/or (b) a potassium cation concentration ofabout 5% to about 40%; wherein the adsorbent bed is operated at a firstpressure (e.g., such that the partial pressure of CO₂ is from about 0.5bar to about 7 bar) and at a first temperature (e.g., about −20° C. toabout 80° C., about 0° C. to about 50° C.) wherein at least a portion ofthe CO₂ in the feed gas mixture is adsorbed by the adsorbent bed andwherein a gaseous product depleted in CO₂ exits the product output endof the adsorbent bed; b) stopping the introduction of the feed gasmixture to the adsorbent bed before breakthrough of CO₂ from the productoutput end of the adsorbent bed; and c) simultaneously heating theadsorbent bed to a second temperature (e.g., about 50° C. to about 250°C., about 75° C. to about 125° C., about 175° C. to about 225° C.)higher than the first temperature and passing a purge gas, substantiallyfree of CO₂, through the adsorbent bed thereby resulting in a reductionin the pressure in the adsorption bed to a second pressure (e.g., suchthat the partial pressure of CO₂ is from about 0.05 bar to about 0.5bar, about 0.08 bar to about 0.3 bar, about 0.09 bar to about 0.4 bar),resulting in desorption of at least a portion of CO₂ from the adsorbentbed and recovering at least a portion of CO₂.

Embodiment 15

The process of any one of embodiments 12-14, wherein the adsorbentmaterial has a working capacity of about 3.0 mmol/cc to about 14.0mmol/cc.

Embodiment 16

A temperature swing adsorption process for separating CO₂ from a feedgas mixture (e.g., natural gas stream), wherein the process comprises:a) subjecting the feed gas mixture comprising CO₂ to an adsorption stepby introducing the feed gas mixture into a feed input end of anadsorbent bed, wherein the adsorbent bed comprises: a feed input end anda product output end; and an adsorbent material selective for adsorbingCO₂, wherein the adsorbent material comprises a zeolite with a frameworkstructure selected from the group consisting of AFT AFX, CAS, EMT, IRR,IRY, ITT, KFI, MWW, PAU, RWY, SFF, STF, TSC, UFI, VFI, and a combinationthereof, having: (a) a Si/Al ratio of about 1 to about 20 or about 1 toabout 10; and/or (b) a potassium cation concentration of about 0% toabout 50% or about 0% to about 40%; wherein the adsorbent bed isoperated at a first pressure (e.g., such that the partial pressure ofCO₂ is from about 0.5 bar to about 3 bar, about 0.5 bar to about 3 bar)and at a first temperature (e.g., about −20° C. to about 80° C., about0° C. to about 50° C.) wherein at least a portion of the CO₂ in the feedgas mixture is adsorbed by the adsorbent bed and wherein a gaseousproduct depleted in CO₂ exits the product output end of the adsorbentbed; b) stopping the introduction of the feed gas mixture to theadsorbent bed before breakthrough of CO₂ from the product output end ofthe adsorbent bed; c) heating the adsorbent bed to a second temperature(e.g., about 150° C. to about 250° C.) higher than the firsttemperature, resulting in desorption of at least a portion of CO₂ fromthe adsorbent bed and recovering at least a portion of CO₂ from theadsorbent bed.

Embodiment 17

The process of embodiment 16, wherein the adsorbent material comprises azeolite with a framework structure selected from the group consisting ofAFX, AFT, KFI, PAU, TSC, UFI, and a combination thereof, having: (a) aSi/Al ratio of about 1 to about 10; and/or (b) a potassium cationconcentration of about 0% to about 40%.

Embodiment 18

A temperature swing adsorption process for separating CO₂ from a feedgas mixture, wherein the process comprises: a) subjecting the feed gasmixture comprising CO₂ to an adsorption step by introducing the feed gasmixture into a feed input end of an adsorbent bed, wherein the adsorbentbed comprises: a feed input end and a product output end; and anadsorbent material selective for adsorbing CO₂, wherein the adsorbentmaterial comprises one or more of the following: (i) a zeolite with aframework structure selected from the group consisting of CHA, FAU, RHO,and a combination thereof, having: (a) a Si/Al ratio of about 1 to about20; and/or (b) a potassium cation concentration of about 0% to about40%; or (ii) a zeolite with a LTA framework structure having: (a) aSi/Al ratio of about 1 to about 20; and/or (b) a potassium cationconcentration of about 5% to about 40%; the adsorbent bed is operated ata first pressure and at a first temperature wherein at least a portionof the CO₂ in the feed gas mixture is adsorbed by the adsorbent bed andwherein a gaseous product depleted in CO₂ exits the product output endof the adsorbent bed; b) stopping the introduction of the feed gasmixture to the adsorbent bed before breakthrough of CO₂ from the productoutput end of the adsorbent bed; c) heating adsorbent bed to a secondtemperature higher than the first temperature, resulting in desorptionof at least a portion of CO₂ from the adsorbent bed and recovering atleast a portion of CO₂ from the adsorbent bed.

Embodiment 19

The process of embodiments 16-18, wherein the adsorbent material has aworking capacity of about 5.0 mmol/cc to about 12.0 mmol/cc.

Embodiment 20

The process of any one of the previous embodiments, wherein theadsorbent bed has open flow channels throughout its entire lengththrough which the feed gas mixture is passed, e.g., a parallel channelcontactor.

EXAMPLES

The following examples are merely illustrative, and do not limit thisdisclosure in any way.

Example 1—Gas Adsorption Simulation Studies

General Simulation Method

Roughly 220 zeolite topologies have been identified experimentally andare recognized by the International Zeolite Association (IZA)(Baerlocher, C.; McCusker, L. B., Database of Zeolite Structures.http://www.iza-structure.org/databases/, accessed on Apr. 14, 2015). Inaddition, large collections of hypothetical zeolite-like materials havebeen generated (Deem, M. W.; Pophale, R.; Cheeseman, P. A.; Earl, D. J.J Phys Chem C 2009, 113, 21353; Pophale, R.; Cheeseman, P. A.; Deem, M.W. Phys Chem Phys 2011, 13, 12407). An important simplification can bemade by noting that only a fraction of the known experimental topologies(and none of the hypothetical materials) have known synthesis routes foraluminosilicate or siliceous materials. Most of the materials selectedfor calculations can be tested experimentally. First ten-membered ring(10MR) zeolites were considered. This choice avoids complicationsassociated with the pore blocking and/or strongly hindered diffusionthat can occur in K-containing zeolites with smaller pores. In the IZAdatabase there are a total of 21 10MR topologies where aluminosilicateor silica analogues have been synthesized experimentally: DAC, EUO, FER,HEU, IMF, ITH, LAU, MFI, MFS, MRE, MTT, MWW, NES, RRO, SFF, STF, STI,SZR, TER, TON, TUN. In addition simulations were performed for 16 othertopologies from the IZA database with large pore volumes (or voidfraction), including three 18MR (IRR, VFI, ITT), one 16MR (IRY), three12MR (FAU, EMT, RWY), and nine 8MR (LTA, TSC, AFT, AFX, CHA, KFI, PAU,RHO, UFI) zeolites. IRR, VFI, ITT, IRY, RWY, and AFT topologies wereincluded because of their large pore volumes, although their siliceousor aluminosilicate analogues have not been synthesized experimentally todate.

For each topology, full optimizations of the siliceous structure wereperformed using the Hill-Sauer force field (Hill, J. R.; Sauer, J. JPhys Chem 1995, 99, 9536). Using these optimized frameworks,aluminosilicate structures were constructed with Si/Al ratios of 1, 2,3, 5, 10, 25, and 50. Si atoms were randomly substituted by Al atomsobeying the Lowenstein's rule (Loewenstein, W. Am Mineral 1954, 39, 92).For the topologies that include odd numbered window sizes (e.g., 3, 5,and 7MR windows), it was therefore impossible to make structures withSi/Al=1, because Si and Al atoms cannot appear alternatively in thesewindows. For these topologies, the lowest Si/Al ratio used was 2 or 3.For each Si/Al ratio, K and/or Na extra-framework cations wereintroduced with the K/(K+Na) ratio chosen to be 0, 16.7, 33.4, 50, 66.7,83.3, and 100%. For 10MR zeolites, this procedure generated 910 distinctmaterials.

The notation ZEO_A_B is used to represent cationic zeolites, where ZEOindicates the topology, A the Si/Al ratio, and B the percentage ofpotassium cations. Siliceous zeolites are denoted ZEO_Si. For instance,MFI 10_50 represents a zeolite material having the MFI topology, a Si/Alratio of 10, and 50% K cations, while MFI_Si represents the siliceousMFI zeolite.

To get reliable cation distributions for each material,pre-equilibration simulations were performed prior to the adsorption ofCO₂. In every material, Al atoms were randomly distributed subject tothe Löwenstein rule (Loewenstein, W. Am Mineral 1954, 39, 92.). Paralleltempering (also known as canonical replica-exchange Monte Carlo) wasused in these simulations (Beauvais, C.; Guerrault, X.; Coudert, F. X.;Boutin, A.; Fuchs, A. H. J Phys Chem B 2004, 108, 399; Earl, D. J.;Deem, M. W. Phys Chem 2005, 7, 3910). For each cationic material, ninereplicas were included in simulations at temperatures of 300, 390, 507,659, 857, 1114, 1448, 1882, 2447 K, respectively. Adjacent temperaturesare in a ratio of 1.3 for each temperature interval, as suggested inprevious work (Beauvais, C.; Guerrault, X.; Coudert, F. X.; Boutin, A.;Fuchs, A. H. J Phys Chem B 2004, 108, 399). The lowest temperature wasroom temperature, and the highest temperature was high enough so as toensure that no replicas become trapped in local energy minima.Reasonable degree of overlap between the potential energy distributionsof neighboring state points was found.

Classical simulations were performed using the RASPA code developed byDubbeldam and co-workers (Dubbeldam, D.; Calero, S.; Ellis, D. E.;Snurr, R. Q. Mol Simul 2015, 1; Dubbeldam, D.; Torres-Knoop, A.; Walton,K. S. Mol Simul 2013, 39, 1253), where the first-principles developedforce fields as described above were used for calculating theinteractions between CO₂ and zeolite as well as the interactions betweencation and framework. Periodic boundary conditions were employed, vdWinteractions were evaluated with the cutoff of 12 Å, and electrostaticenergies were calculated using Ewald summation (Allen, M. P.; Tildesley,D. J. Computer Simulation of Liquids; Clarendon Press: Oxford, U. K.,1987; Frenkel, D.; Smit, B. Understanding Molecular Simulation: FromAlgorithms to Applications 2nd ed.; Academic Press: San Diego, Calif.,2002). Truncated potentials with tail corrections were used. During thesimulations all framework atoms were fixed at their crystallographicpositions while cations were allow to move.

Adsorption isotherms of CO₂ in zeolites were predicted computationallyusing standard Grand Canonical Monte Carlo (GCMC) methods, where volume(V), temperature (T), and chemical potential (μ) are held constant andthe number of adsorbate molecules fluctuates. The chemical potential isdetermined from the fugacity, and the fugacity coefficients are computedusing the Peng-Robinson equation of state (Robinson, D. B.; Peng, D. Y.;Chung, S. Y. K. Fluid Phase Equilibr 1985, 24, 25). Isosteric heats ofadsorption, Qst, defined as the difference in the partial molar enthalpyof the adsorption between the gas phase and the adsorbed phase, wereobtained during GCMC simulations using (Snurr, R. Q.; Bell, A. T.;Theodorou, D. N. J Phys Chem 1993, 97, 13742)

$Q_{st} = {{RT} - \frac{< {NV} > {- {< N > < V >}}}{< N^{2} > {- {< N >^{2}}}}}$where T is the temperature, R is the gas constant, < > denotes theensemble average, N is the number of adsorbed molecules, and V is thesum of the interactions of all adsorbed molecules among themselves andwith the zeolite. Isosteric heats of adsorption at the limit of zeroloading, Q_(st) ⁰, were calculated using NVT ensemble, where N=1(Burtch, N. C.; Jasuja, H.; Dubbeldam, D.; Walton, K. S. J Am Chem Soc2013, 135, 7172).

The number of simulation cycles were tested to ensure that the predictedvalues of these adsorption properties were well converged (withdeviation less than 5%). For cation pre-equilibration 100,000 cycleswere used, while for CO₂ adsorption 25,000 cycles were used to guaranteeequilibration and the following 25,000 cycles were used to sample thedesired thermodynamics properties.

Some topologies, for example, FAU and LTA, include regions such assodalite cages that are inaccessible for CO₂ molecules. These regionswere blocked in simulations to avoid spurious adsorption of CO₂ in theseregions.

For the structures with low Si/Al ratios, the blockage effect from K+cations locating at 8MR windows may exist, and GCMC simulations cannotaccount it. So that was kept it in mind when these structures werechosen for CO₂ capture.

Void fractions of zeolite structures were computed from Widom particleinsertion using Helium. The pore volume is the void fraction times theunit cell volume. Surface areas were computed using N₂ as the probemolecule. For the calculations of pore volumes and surface areas, theClay Force Field (CLAYFF) was used for the atoms of the zeolite, forcefield parameters from the previous work were used for He—He interactions(Talu, O.; Myers, A. L. Colloid Surface A 2001, 187, 83), and the TraPPEwas used for N₂-N₂ interactions (Potoff, J. J.; Siepmann, J. I. Aiche J2001, 47, 1676). Lorentz-Berthelot mixing rules was applied for thecross species interactions (Cygan, R. T.; Liang, J.-J.; Kalinichev, A.G. J Phys Chem B 2004, 108, 1255).

Pore sizes including the largest cavity diameter (LCD) and the porelimiting diameter (PLD) were computed using Zeo++(Willems, T. F.;Rycroft, C.; Kazi, M.; Meza, J. C.; Haranczyk, M. Micropor Mesopor Mat2012, 149, 134), where the radii of O, Si, and Al atoms in zeolitestructures were adjusted to be 1.35 Å and the default CCDC radii wereused for Na and K (2.27 and 2.75 Å, respectively).

In all simulations, framework atoms were fixed and extra-frameworkcations were allowed to move. Cation positions were determined usingparallel tempering method prior to CO₂ adsorption. GCMC simulations wereperformed to predict the adsorbed amount of CO₂ and isosteric heat ofadsorption at each condition in Table 1, while single-molecule NVT MonteCarlo simulations were used to compute the isosteric heat of adsorptionat zero loading (Qsto) (Burtch, N. C.; Jasuja, H.; Dubbeldam, D.;Walton, K. S. J Am Chem Soc 2013, 135, 7172). Geometrical properties ofthe empty zeolite structures were calculated, including pore size interms of pore limiting diameter (PLD), largest cavity diameter (LPD),accessible pore volume, and surface area.

To illustrate the approach, FIG. 1 a-1 d shows the results for MWWzeolites topology. This figure shows that for each process the CO₂working capacity varies with Si/Al ratio and cation composition, withthe Si/Al ratio having a stronger influence on the working capacity.

For PSA the siliceous form of MMW has higher working capacity than thecationic analogues with high Si/Al ratios, which are in turn better thanthose with medium and low Si/Al ratios. Even though the adsorbed amountsof CO₂ in the cationic forms of MWW were larger than in the siliceousform at the adsorption condition, the cationic structures have lowerworking capacities due to the larger residual amounts of CO₂ at thedesorption condition. The stronger CO₂ interactions created by thepresence of extra-framework cations resulted in a trade-off between hightotal adsorption capacities and reduced working capacities.

In VSA (FIG. 1 b ), however, the cationic forms of MWW with Si/Al ratioaround 25 perform better than those with lower and higher Si/Al ratios,including the siliceous analog of MWW. In PTSA and VTSA, the optimalSi/Al ratios lie at 50 and 10. The optimal MWW structures are determinedto be MWW_Si, MWW_25_100, MWW_50_100, and MWW_10_17 for PSA, VSA, PTSA,and VTSA, respectively. The results in FIG. 1 represent a detailed,quantitative description of CO₂ adsorption in a wide range of MWWzeolites that would require enormously time-consuming synthesis andtesting to establish experimentally. This kind of data, which we havecalculated for all of the zeolite topologies listed above, greatlyextends the number of zeolites for which thorough information isavailable regarding CO₂ adsorption. Using our results, we determined theoptimal composition for each zeolite topology in each process, ascharacterized by CO₂ working capacity. Simulations were performed forprocess conditions listed in Table 4.

Example 1A—PSA1

Conditions:

Adsorption: 300K, 5 bar

Desorption: 300 K, 1 bar

Optimal boundaries Si/Al Topology ratio K/(K + Na)% RWY  3-10 0-100 IRY 3-25 0-100 FAU 25-inf 0-100 TSC 25-inf 0-100 IRR  3-25 0-100 EMT 25-inf0-100 RHO 25-inf 0-100 UFI 25-inf 0-100 CHA 25-inf 0-100 AFT 25-inf0-100 LTA 25-inf 0-100 AFX 25-inf 0-100 ITT  3-25 0-100 KFI 25-inf 0-100VFI  3-25 0-100

The results are shown in Table 11

TABLE 11 PSA1 Results ΔN N^(ads) N^(des) LCD PLD mmol/ mmol/ mmol/Q_(st) ^(ads) Q_(st) ^(des) Q_(st) ⁰ (Di) (Df) Accessible density Q_(st)^(ave) Zeolite cc cc cc kJ/mol kJ/mol kJ/mol Å Å volume- kg/m3 kJ/molRWY_5_100 6.49 10.90 4.41 26 27 38 12.69 6.45 0.67 867.28 27 IRY_10_1004.98 8.42 3.44 26 25 44 10.55 6.71 0.58 1180.48 25 FAU_50_67 4.40 6.321.92 26 24 35 10.89 6.94 0.44 1292.53 25 TSC_50_83 4.36 6.68 2.32 26 2738 15.19 3.89 0.46 1297.36 26 IRR_10_100 4.25 7.35 3.10 25 26 33 11.498.07 0.54 1173.74 25 EMT_50_100 4.12 6.08 1.96 26 24 36 11.30 6.94 0.441294.05 25 RHO_Si 4.02 7.01 2.99 27 26 29 10.62 3.82 0.46 1386.76 27UFI_Si 4.01 6.85 2.84 30 26 28 10.33 3.41 0.44 1444.84 28 CHA_Si 3.866.60 2.74 30 26 22 7.23 3.82 0.42 1465.94 28 AFT_Si 3.77 6.78 3.02 30 2728 7.59 3.67 0.42 1469.05 28 LTA_50_67 3.75 5.53 1.78 26 25 44 10.953.72 0.40 1362.60 26 AFX_Si 3.72 6.96 3.24 30 27 29 7.56 3.66 0.421468.58 28 ITT_10_100 3.60 7.07 3.47 25 27 38 11.58 8.02 0.49 1286.64 26KFI_Si 3.58 7.47 3.89 31 31 29 10.74 4.06 0.42 1458.36 31 VFI_10_1003.46 5.38 1.92 25 25 34 10.38 7.62 0.39 1457.56 25 SFF_Si 3.14 5.33 2.2029 25 21 7.62 5.49 0.37 1605.67 27 STF_Si 3.13 6.02 2.89 33 27 22 7.675.52 0.38 1603.81 30 PAU_Si 3.00 7.20 4.20 32 31 30 10.55 3.82 0.381535.92 32 MWW_Si 2.91 4.72 1.81 25 23 22 9.76 4.94 0.40 1538.37 24ITH_Si 2.50 4.64 2.14 28 26 23 6.74 4.74 0.32 1635.73 27 NES_Si 2.394.27 1.88 28 24 21 7.05 4.85 0.34 1600.43 26 TUN_Si 2.32 4.61 2.29 28 2523 8.72 5.51 0.34 1628.85 26 TER_Si 2.24 4.75 2.51 28 26 23 6.98 5.170.34 1649.03 27 FER_Si 2.23 4.56 2.33 30 27 24 6.33 4.66 0.30 1704.70 29MFS_Si 2.19 4.41 2.22 30 27 24 6.82 5.47 0.30 1685.27 28 IMF_Si 2.094.27 2.18 28 25 22 7.44 5.44 0.33 1648.76 26 STI_Si 2.08 4.37 2.29 28 2523 6.04 5.01 0.35 1607.43 27 SZR_Si 1.95 4.19 2.24 31 28 20 6.26 4.620.28 1696.17 30 MFI_Si 1.92 4.36 2.44 28 26 24 6.85 5.55 0.32 1654.46 27EUO_Si 1.88 3.73 1.85 28 25 23 7.10 4.88 0.32 1638.00 26 DAC_Si 1.816.53 4.72 34 32 33 5.34 3.85 0.31 1686.90 33 LAU_Si 1.81 4.43 2.62 30 2824 6.04 4.10 0.30 1689.47 29 RRO_Si 1.59 5.83 4.24 34 33 29 4.67 4.190.29 1688.62 34 TON_Si 1.48 3.86 2.38 32 29 25 5.77 5.19 0.23 1759.92 31MTT_Si 1.42 3.38 1.96 31 28 25 6.30 5.19 0.23 1760.11 29 CAS_50_17 1.334.45 3.12 35 35 35 4.97 2.93 0.16 1846.57 35 HEU_50_100 1.21 5.26 4.0532 31 38 5.83 4.17 0.32 1666.11 32 MRE_Si 1.02 1.86 0.85 24 22 20 6.665.74 0.20 1779.94 23

Example 1B—PSA2

Conditions:

Adsorption: 300K, 20 bar

Desorption: 300 K, 1 bar

Optimal boundaries Si/Al Topology ratio K/(K + Na)% RWY  3-25 0-100 IRY25-inf 0-100 IRR 25-inf 0-100 TSC 25-inf 0-100 ITT 25-inf 0-100 FAU25-inf 0-100 EMT 25-inf 0-100 LTA 25-inf 0-100 RHO 25-inf 0-100 VFI25-inf 0-100 UFI 25-inf 0-100 CHA 25-inf 0-100 AFT 25-inf 0-100 AFX25-inf 0-100 KFI 25-inf 0-100

The results are shown in Table 12

TABLE 12 PSA2 Results ΔN N^(ads) N^(des) LCD PLD mmol/ mmol/ mmol/Q_(st) ^(ads) Q_(st) ^(des) Q_(st) ⁰ (Di) (Df) Accessible density Q_(st)^(ave) Zeolite cc cc cc kJ/mol kJ/mol kJ/mol Å Å volume- kg/m³ kJ/molRWY_10_100 11.43 13.90 2.47 28 24 29 13.06 6.45 0.69 828.60 26IRY_50_100 9.74 10.58 0.84 26 19 25 11.28 9.31 0.61 1129.92 23IRR_50_100 8.92 9.90 0.98 25 20 24 14.84 9.21 0.57 1123.25 23 TSC_Si7.96 9.46 1.49 29 26 28 16.07 3.89 0.47 1281.40 27 ITT_Si 7.64 8.58 0.9424 20 21 13.84 12.34 0.53 1217.09 22 FAU_Si 7.31 8.39 1.09 29 20 1810.89 6.94 0.45 1277.51 25 EMT_Si 7.17 8.26 1.09 29 20 19 11.30 6.950.45 1277.26 25 LTA_Si 6.70 7.55 0.86 29 21 19 10.95 3.72 0.42 1346.7725 RHO_Si 6.50 9.49 2.99 30 26 29 10.62 3.82 0.46 1386.76 28 VFI_Si 6.256.55 0.30 24 15 13 12.29 11.61 0.42 1379.02 19 UFI_Si 5.97 8.80 2.84 3126 28 10.33 3.41 0.44 1444.84 29 CHA_Si 5.89 8.63 2.74 31 26 22 7.233.82 0.42 1465.94 28 AFT_Si 5.79 8.80 3.02 31 27 28 7.59 3.67 0.421469.05 29 AFX_Si 5.56 8.80 3.24 32 27 29 7.56 3.66 0.42 1468.58 30KFI_Si 5.28 9.17 3.89 30 31 29 10.74 4.06 0.42 1458.36 30 MWW_Si 4.956.76 1.81 28 23 22 9.76 4.94 0.40 1538.37 25 PAU_Si 4.66 8.86 4.20 31 3130 10.55 3.82 0.38 1535.92 31 SFF_Si 4.60 6.80 2.20 30 25 21 7.62 5.490.37 1605.67 27 STF_Si 4.56 7.45 2.89 34 27 22 7.67 5.52 0.38 1603.81 31CAS_25_83 1.88 4.20 2.32 33 34 39 4.97 2.93 0.15 1873.34 34

Example 1C—PTSA1

Conditions:

Adsorption: 300K, 5 bar

Desorption: 373 K, 1 bar

Optimal boundaries Si/Al Topology ratio K/(K + Na)% RWY  3-10 0-100 IRY 2-10 0-100 IRR  2-25 0-100 FAU  2-25 0-100 KFI 10-inf 0-100 RHO 10-inf0-100 TSC  3-25 0-100 UFI 10-inf 0-100 EMT  2-25 0-100 ITT  2-25 0-100PAU 25-inf 0-100 VFI  1-5 0-100 AFX 25-inf 0-100 AFT 25-inf 0-100 CHA10-inf 0-100

The results are shown in Table 13

TABLE 13 PTSA1 Results ΔN N^(ads) N^(des) LCD PLD mmol/ mmol/ mmol/Q_(st) ^(ads) Q_(st) ^(des) Q_(st) ⁰ (Di) (Df) Accessible density Q_(st)^(ave) Zeolite cc cc cc kJ/mol kJ/mol kJ/mol Å Å volume- kg/m³ kJ/molRWY_3_17 11.17 12.84 1.67 29 31 35 12.43 6.45 0.68 864.94 30 IRY_3_08.68 12.37 3.70 33 36 48 9.64 6.69 0.58 1216.97 35 IRR_5_50 7.76 9.561.80 28 33 43 12.01 7.98 0.54 1201.02 31 FAU_5_83 7.12 8.58 1.46 34 3238 8.03 5.38 0.41 1402.97 33 KFI_25_100 6.99 8.22 1.23 33 33 36 10.744.06 0.40 1494.29 33 RHO_25_83 6.98 8.17 1.19 29 31 53 10.62 3.82 0.451418.05 30 TSC_10_17 6.87 8.11 1.25 28 34 46 13.46 3.89 0.45 1329.29 31UFI_25_100 6.82 7.92 1.10 33 30 35 8.76 3.41 0.43 1480.44 32 EMT_5_336.74 8.74 2.00 33 33 44 9.60 6.79 0.43 1373.43 33 ITT_5_50 6.57 8.862.29 29 34 46 11.02 7.68 0.48 1318.02 32 PAU_50_67 6.40 7.77 1.37 33 3239 9.61 3.82 0.37 1552.23 33 VFI_1_0 6.38 7.89 1.52 31 33 36 9.67 8.690.41 1630.18 32 AFX_50_0 6.36 7.57 1.22 32 31 37 7.56 3.66 0.41 1479.7231 AFT_50_33 6.25 7.37 1.12 30 30 35 7.59 3.67 0.41 1482.92 30 CHA_25_506.24 7.52 1.28 32 31 36 7.23 3.82 0.41 1492.96 31 LTA_10_33 5.87 6.941.07 31 31 44 9.42 3.72 0.40 1401.43 31 STF_Si 5.50 6.02 0.52 33 23 227.67 5.52 0.38 1603.81 28 DAC_Si 5.42 6.53 1.11 34 31 33 5.34 3.85 0.311686.90 32 RRO_Si 5.06 5.83 0.77 34 30 29 4.67 4.19 0.29 1688.62 32SFF_50_100 4.94 5.65 0.71 30 27 32 7.62 5.49 0.36 1625.45 29 MWW_25_1004.90 5.83 0.93 29 29 36 9.76 4.77 0.37 1575.44 29 ITH_Si 4.22 4.64 0.4228 24 23 6.74 4.74 0.32 1635.73 26 TER_Si 4.20 4.75 0.55 28 24 23 6.985.17 0.34 1649.03 26 STI_10_100 4.18 5.86 1.68 33 35 47 6.04 4.33 0.301698.98 34 NES_50_100 4.15 4.82 0.66 30 27 37 7.05 4.85 0.33 1620.85 29CAS_Si 4.11 4.64 0.53 36 34 34 10.33 3.41 0.17 1833.03 35 TUN_Si 4.104.61 0.52 28 24 23 8.72 5.51 0.34 1628.85 26 HEU_Si 4.07 5.26 1.18 31 3031 5.83 4.17 0.33 1646.28 31 FER_Si 4.05 4.56 0.51 30 25 24 6.33 4.660.30 1704.70 28 MFS_Si 3.97 4.41 0.44 30 24 24 6.82 5.47 0.30 1685.27 27LAU_Si 3.81 4.43 0.63 30 26 24 6.04 4.10 0.30 1689.47 28 MFI_Si 3.794.36 0.56 28 25 24 6.85 5.55 0.32 1654.46 26 SZR_Si 3.78 4.19 0.41 31 2520 6.26 4.62 0.28 1696.17 28 IMF_Si 3.78 4.27 0.49 28 23 22 7.44 5.440.33 1648.76 25 EUO_25_100 3.58 4.38 0.80 31 30 35 7.10 4.88 0.281677.21 30 TON_Si 3.32 3.86 0.54 32 26 25 5.77 5.19 0.23 1759.92 29MTT_Si 2.89 3.38 0.49 31 26 25 6.30 5.19 0.23 1760.11 28 MRE_10_100 1.662.28 0.62 33 33 38 6.43 3.05 0.16 1881.31 33

Example 1D—PTSA2

Conditions:

Adsorption: 300K, 20 bar

Desorption: 373 K, 1 bar

Optimal boundaries Si/Al Topology ratio K/(K + Na)% RWY  3-10 0-100 IRY 2-25 0-100 IRR  2-25 0-100 TSC 10-inf 0-100 ITT 10-inf 0-100 RHO 25-inf0-100 FAU  2-25 0-100 EMT  3-inf 0-100 KFI 25-inf 0-100 AFT 25-inf 0-100UFI 25-inf 0-100 CHA 25-inf 0-100 AFX 25-inf 0-100 PAU 25-inf 0-100 VFI 1-5 0-100

The results are shown in Table 14

TABLE 14 PTSA2 Results ΔN N^(ads) N^(des) LCD PLD mmol/ mmol/ mmol/Q_(st) ^(ads) Q_(st) ^(des) Q_(st) ⁰ (Di) (Df) Accessible density Q_(st)^(ave) Zeolite cc cc cc kJ/mol kJ/mol kJ/mol Å Å volume- kg/m³ kJ/molRWY_3_17 14.39 16.06 1.67 32 31 35 12.43 6.45 0.68 864.94 32 IRY_10_6711.21 12.13 0.92 30 28 42 10.82 7.23 0.59 1171.74 29 IRR_10_33 10.3211.35 1.03 28 30 39 12.18 9.07 0.56 1155.96 29 TSC_25_33 9.31 9.93 0.6229 30 40 14.97 3.89 0.46 1304.09 29 ITT_25_50 8.98 9.53 0.56 27 26 4213.55 9.57 0.52 1239.83 27 RHO_Si 8.97 9.49 0.52 30 26 29 10.62 3.820.46 1386.76 28 FAU_5_83 8.65 10.11 1.46 34 32 38 8.03 5.38 0.41 1402.9733 EMT_10_100 8.40 9.25 0.84 33 29 34 9.93 6.59 0.42 1350.71 31 KFI_Si8.39 9.17 0.78 30 28 29 10.74 4.06 0.42 1458.36 29 AFT_Si 8.18 8.80 0.6231 25 28 7.59 3.67 0.42 1469.05 28 UFI_Si 8.16 8.80 0.64 31 26 28 10.333.41 0.44 1444.84 29 CHA_Si 8.10 8.63 0.53 31 23 22 7.23 3.82 0.421465.94 27 AFX_Si 8.10 8.80 0.70 32 27 29 7.56 3.66 0.42 1468.58 30PAU_Si 8.02 8.86 0.84 31 29 30 10.55 3.82 0.38 1535.92 30 VFI_1_0 7.679.19 1.52 31 33 36 9.67 8.69 0.41 1630.18 32 LTA_50_83 7.45 7.89 0.44 2925 44 10.95 3.72 0.41 1362.60 27 STF_Si 6.93 7.45 0.52 34 23 22 7.675.52 0.38 1603.81 29 MWW_50_100 6.47 7.15 0.69 30 26 30 9.76 4.94 0.391558.59 28 SFF_Si 6.37 6.80 0.42 30 22 21 7.62 5.49 0.37 1605.67 26CAS_Si 4.43 4.96 0.53 35 34 34 10.33 3.41 0.17 1833.03 35

Example 1E—VSA

Conditions:

Adsorption: 300K, 1 bar

Desorption: 300K, 0.1 bar

Optimal boundaries Si/Al Topology ratio K/(K + Na)% RWY  3-10 0-100 IRY 2-10 0-100 FAU  2-25 0-100 UFI 10-inf 0-100 KFI 10-inf 0-100 IRR  1-100-100 EMT  2-10 0-100 RHO  3-50 0-100 AFX 10-inf 0-100 PAU 25-inf 0-100VFI  1-5 0-100 AFT 10-inf 0-100 RRO 25-inf 0-100 CHA 10-inf 0-100 DAC25-inf 0-100

The results are shown in Table 15

TABLE 15 VSA Results ΔN N^(ads) N^(des) LCD PLD mmol/ mmol/ mmol/ Q_(st)^(ads) Q_(st) ^(des) Q_(st) ⁰ (Di) (Df) Accessible density Q_(st) ^(ave)Zeolite cc cc cc kJ/mol kJ/mol kJ/mol Å Å volume- kg/m³ kJ/mol RWY_3_175.34 7.33 1.99 30 34 35 12.43 6.45 0.68 864.94 32 IRY_3_83 4.48 7.543.06 30 35 47 10.18 5.45 0.54 1278.16 33 FAU_5_100 4.28 6.03 1.75 32 3435 7.73 5.73 0.41 1411.84 33 UFI_25_100 3.98 5.20 1.22 32 32 35 8.763.41 0.43 1480.44 32 KFI_25_100 3.94 5.46 1.52 33 34 36 10.74 4.06 0.401494.29 33 IRR_3_100 3.79 6.47 2.68 31 37 43 12.81 7.31 0.50 1284.82 34EMT_5_83 3.78 5.73 1.95 31 35 41 9.14 6.38 0.41 1401.81 33 RHO_10_503.59 6.66 3.06 32 36 56 8.94 3.82 0.43 1449.17 34 AFX_25_33 3.54 5.491.95 32 34 37 7.56 3.66 0.40 1494.57 33 PAU_50_33 3.53 5.26 1.73 33 3350 10.01 3.82 0.37 1549.18 33 VFI_1_0 3.52 5.47 1.94 32 35 36 9.67 8.690.41 1630.18 34 AFT_25_83 3.51 4.94 1.43 31 32 42 7.59 3.67 0.40 1501.7332 RRO_Si 3.43 4.24 0.80 33 31 29 4.67 4.19 0.29 1688.62 32 CHA_25_833.40 4.70 1.30 31 32 34 7.23 3.82 0.41 1497.78 32 DAC_Si 3.39 4.72 1.3232 32 33 5.34 3.85 0.31 1686.90 32 LTA_5_50 3.30 5.54 2.24 33 36 46 8.173.71 0.39 1458.46 34 TSC_5_0 3.27 6.22 2.94 32 38 48 12.33 3.40 0.451359.20 35 ITT_3_50 3.16 7.06 3.90 31 39 53 10.45 7.76 0.46 1368.48 35STF_50_100 3.13 3.94 0.81 30 30 33 7.67 5.52 0.36 1623.58 30 HEU_Si 2.844.14 1.30 31 32 31 5.83 4.17 0.33 1646.28 31 MWW_10_100 2.72 4.90 2.1833 35 49 7.25 4.45 0.34 1625.99 34 SFF_25_67 2.69 4.01 1.32 30 33 517.62 5.49 0.35 1639.66 32 CAS_Si 2.61 3.37 0.76 35 35 34 10.33 3.41 0.171833.03 35 TER_50_100 2.31 3.16 0.86 28 30 33 6.98 5.17 0.32 1669.26 29STI_10_83 2.29 4.46 2.17 34 36 47 6.04 4.22 0.31 1692.28 35 MFS_25_1002.25 3.58 1.33 33 34 40 6.82 4.50 0.28 1725.88 33 TUN_50_100 2.23 2.940.71 27 29 31 8.72 5.51 0.32 1648.92 28 NES_10_67 2.22 4.56 2.34 35 3751 7.04 4.02 0.30 1678.83 36 FER_50_100 2.18 2.96 0.78 30 31 35 6.334.65 0.29 1725.23 30 ITH_25_100 2.17 3.44 1.26 30 34 40 6.74 3.93 0.291675.66 32 LAU_Si 2.15 2.62 0.47 28 26 24 6.04 4.10 0.30 1689.47 27MFI_50_100 2.13 2.97 0.84 28 30 43 6.85 5.55 0.31 1674.84 29 SZR_50_832.05 2.82 0.78 30 32 41 6.26 4.62 0.27 1715.03 31 EUO_25_100 1.98 2.830.84 29 32 35 7.10 4.88 0.28 1677.21 31 IMF_50_100 1.96 2.83 0.87 27 3033 7.44 5.44 0.31 1668.62 29 TON_Si 1.95 2.38 0.43 29 27 25 5.77 5.190.23 1759.92 28 MTT_Si 1.59 1.96 0.37 28 26 25 6.30 5.19 0.23 1760.11 27MRE_10_100 0.96 1.70 0.74 33 34 38 6.43 3.05 0.16 1881.31 34

Example 1F—VTSA1

Conditions:

Adsorption: 300K, 1 bar

Desorption: 373K, 0.1 bar

Optimal boundaries Si/Al Topology ratio K/(K + Na)% IRY 2-10 0-100 IRR2-10 0-100 FAU 1-10 0-100 EMT 1-10 0-100 RWY 3-10 0-100 ITT 2-10 0-100KFI 1-10 0-100 RHO 1-25 0-100 TSC 1-5 0-100 PAU 1-25 0-100 CHA 1-250-100 UFI 2-10 0-100 AFX 1-25 0-100 LTA 1-5 0-100 AFT 2-10 0-100

The results are shown in Table 16

TABLE 16 VTSA1 Results ΔN N^(ads) N^(des) LCD PLD mmol/ mmol/ mmol/Q_(st) ^(ads) Q_(st) ^(des) Q_(st) ⁰ (Di) (Df) Accessible density Q_(st)^(ave) Zeolite cc cc cc kJ/mol kJ/mol kJ/mol Å Å volume- kg/m³ kJ/molIRY_2_0 8.78 10.07 1.29 32 42 48 11.00 6.80 0.58 1250.14 37 IRR_2_0 7.829.19 1.37 32 43 50 11.01 8.86 0.54 1244.85 38 FAU_2_33 7.51 8.17 0.66 3740 44 7.77 4.29 0.42 1469.88 39 EMT_2_0 7.26 8.36 1.09 38 42 51 8.754.48 0.43 1432.34 40 RWY_3_17 7.14 7.33 0.20 30 31 35 12.43 6.45 0.68864.94 31 ITT_2_17 6.92 8.33 1.41 33 45 54 10.78 7.88 0.48 1383.09 39KFI_3_0 6.83 7.97 1.14 39 44 50 8.38 3.25 0.37 1591.16 41 RHO_5_0 6.718.39 1.68 36 46 58 9.03 3.82 0.44 1470.95 41 TSC_1_0 6.60 7.55 0.96 3444 54 12.11 1.49 0.42 1514.78 39 PAU_10_33 6.41 7.39 0.98 36 44 54 8.553.82 0.35 1598.89 40 CHA_1_0 6.33 7.53 1.20 43 45 58 4.47 1.18 0.321732.93 44 UFI_2_0 6.14 7.65 1.52 35 45 49 7.86 2.25 0.42 1619.58 40AFX_10_17 6.01 6.68 0.67 35 41 46 7.56 3.66 0.39 1523.45 38 LTA_1_0 5.937.42 1.49 38 46 48 7.60 1.49 0.38 1592.05 42 AFT_5_0 5.78 7.53 1.74 3846 57 6.82 3.67 0.37 1558.23 42 VFI_2_0 5.31 5.68 0.38 32 38 45 9.708.26 0.40 1546.46 35 STF_5_0 5.24 6.84 1.59 41 45 53 6.13 3.05 0.341700.80 43 SFF_3_0 5.05 7.24 2.19 43 47 56 6.46 4.03 0.33 1751.88 45MWW_2_33 4.87 6.70 1.83 40 46 61 7.35 1.87 0.31 1770.73 43 STI_2_0 4.827.18 2.36 45 49 56 4.92 2.86 0.30 1802.60 47 DAC_50_17 4.75 5.06 0.31 3338 47 5.34 3.85 0.30 1700.19 36 RRO_10_83 4.57 5.22 0.64 38 44 54 4.662.98 0.23 1777.50 41 NES_2_0 4.47 7.03 2.56 45 49 59 5.57 3.10 0.301794.39 47 HEU_25_17 4.11 4.52 0.41 34 39 44 5.83 4.11 0.32 1672.23 36MFS_10_17 4.04 4.90 0.86 36 44 54 6.82 3.68 0.28 1747.71 40 FER_10_333.79 4.52 0.74 35 43 51 6.32 3.25 0.27 1774.17 39 SZR_5_67 3.77 4.781.01 42 46 58 5.49 2.92 0.21 1849.39 44 EUO_3_0 3.77 5.67 1.91 38 48 576.00 3.26 0.28 1787.16 43 ITH_10_17 3.74 4.70 0.96 34 44 54 6.74 3.930.29 1696.30 39 TER_10_17 3.66 4.88 1.22 35 44 63 6.98 3.24 0.30 1709.9739 TUN_10_67 3.60 4.09 0.48 33 39 46 6.99 3.52 0.29 1709.50 36 LAU_10_03.44 4.55 1.11 35 44 59 6.04 3.44 0.27 1745.57 40 MFI_10_33 3.34 4.230.88 34 43 57 6.85 3.02 0.29 1722.60 39 CAS_Si 3.31 3.37 0.06 35 34 3410.33 3.41 0.17 1833.03 35 IMF_10_0 3.28 4.33 1.04 35 43 55 7.44 3.240.30 1702.98 39 MTT_10_83 2.60 2.93 0.33 35 40 43 6.29 2.92 0.19 1853.1938 TON_25_0 2.46 2.91 0.46 32 42 53 5.77 5.19 0.22 1783.96 37 MRE_2_02.10 3.24 1.14 43 48 51 4.85 2.96 0.18 1996.05 45

Example 1G—VTSA2

Conditions:

Adsorption: 300K, 1 bar

Desorption: 473K, 0.2 bar

Optimal boundaries Si/Al Topology ratio K/(K + Na)% IRY 2-10 0-100 FAU1-10 0-100 EMT 1-10 0-100 IRR 2-5 0-100 ITT 2-10 0-100 RHO 1-10 0-100PAU 2-10 0-100 KFI 1-10 0-100 UFI 1-5 0-100 TSC 1-10 0-100 CHA 1-100-100 AFT 1-10 0-100 AFX 1-10 0-100 RWY 3-10 0-100 LTA 1-10 0-100

The results are shown in Table 17

TABLE 17 VTSA2 Results ΔN N^(ads) N^(des) LCD PLD mmol/ mmol/ mmol/Q_(st) ^(ads) Q_(st) ^(des) Q_(st) ⁰ (Di) (Df) Accessible density Q_(st)^(ave) Zeolite cc cc cc kJ/mol kJ/mol kJ/mol Å Å volume- kg/m³ kJ/molIRY_2_0 9.88 10.07 0.19 32 39 48 11.00 6.80 0.58 1250.14 36 FAU_1_0 9.289.62 0.34 40 45 52 7.60 3.01 0.41 1510.18 43 EMT_1_0 9.09 9.51 0.42 3646 54 8.74 3.05 0.41 1509.89 41 IRR_2_0 8.97 9.19 0.22 32 41 50 11.018.86 0.54 1244.85 37 ITT_2_0 8.36 8.65 0.28 31 44 57 10.27 8.41 0.491364.86 38 RHO_3_0 8.19 8.53 0.34 36 49 58 7.73 2.44 0.42 1513.04 43PAU_5_0 8.00 8.47 0.47 41 52 61 7.49 3.19 0.33 1629.16 47 KF-_3_0 7.807.97 0.16 39 41 50 8.38 3.25 0.37 1591.16 40 UFI_2_0 7.44 7.65 0.21 3543 49 7.86 2.25 0.42 1619.58 39 TSC_1_0 7.42 7.55 0.13 34 40 54 12.111.49 0.42 1514.78 37 CHA_1_0 7.40 7.53 0.14 43 43 58 4.47 1.18 0.321732.93 43 AFT_3_0 7.37 7.73 0.36 39 47 56 5.67 3.67 0.36 1602.83 43AFX_3_0 7.28 7.57 0.29 43 45 53 6.07 2.24 0.36 1602.31 44 RWY_3_17 7.287.33 0.06 30 28 35 12.43 6.45 0.68 864.94 29 LTA_1_0 7.22 7.42 0.20 3842 48 7.60 1.49 0.38 1592.05 40 SFF 2 0 6.98 7.50 0.51 45 47 54 5.673.17 0.33 1800.62 46 MWW_2_0 6.82 7.41 0.59 40 50 58 7.71 2.40 0.351725.15 45 STF_2_0 6.62 7.14 0.52 44 48 55 5.56 3.07 0.33 1798.92 46VFI_2_0 5.61 5.68 0.07 32 35 45 9.70 8.26 0.40 1546.46 33 CAS_2_0 3.974.23 0.25 43 60 67 3.86 1.96 0.14 2055.60 51

Example 1H—VTSA3

Conditions:

Adsorption: 300K, 5 bar

Desorption: 473K, 0.2 bar

The results are shown in Table 18

TABLE 18 VTSA3 Results ΔN Zeolite mmol/cc RWY_3_17 12.78 IRY_2_0 12.74IRR_2_0 11.60 FAU_1_0 10.76 ITT_2_0 10.51 EMT_1_0 10.34 RHO_5_0 9.73TSC_1_0 9.23 PAU_5_0 8.99 KFI_5_0 8.90 UFI_2_0 8.56 AFT_5_0 8.39 AFX_5_08.37 LTA_1_0 8.12 CHA_10_0 7.95 VFI_1_0 7.85 SFF_2_0 7.69 MWW_2_0 7.68STF_5_0 7.43 CAS_Si 4.62

Example 1I—TSA

Conditions:

Adsorption: 300K, 1 bar

Desorption: 473K, 1 bar

Optimal boundaries Si/Al Topology ratio K/(K + Na)% IRY 2-10 0-100 IRR2-10 0-100 FAU 1-10 0-100 EMT 1-10 0-100 ITT 2-10 0-100 RHO 1-25 0-100KFI 1-10 0-100 RWY 1-10 0-100 PAU 1-25 0-100 TSC 1-10 0-100 CHA 1-100-100 UFI 1-10 0-100 LTA 1-10 0-100 AFX 1-10 0-100 AFT 1-10 0-100

The results are shown in Table 19

TABLE 19 TSA Results ΔN N^(ads) N^(des) LCD PLD mmol/ mmol/ mmol/ Q_(st)^(ads) Q_(st) ^(des) Q_(st) ⁰ (Di) (Df) Accessible density Q_(st) ^(ave)Zeolite cc cc cc kJ/mol kJ/mol kJ/mol Å Å volume- kg/m³ kJ/mol IRY_2_09.21 10.07 0.86 32 39 48 11.00 6.80 0.58 1250.14 36 IRR_2_0 8.26 9.190.94 32 40 50 11.01 8.86 0.54 1244.85 36 FAU_1_0 8.21 9.62 1.41 40 45 527.60 3.01 0.41 1510.18 43 EMT_1_0 7.93 9.51 1.59 36 45 54 8.74 3.05 0.411509.89 41 ITT_2_0 7.53 8.65 1.12 31 43 57 10.27 8.41 0.49 1364.86 37RHO_5_0 7.34 8.39 1.05 36 44 58 9.03 3.82 0.44 1470.95 40 KFI_3_0 7.257.97 0.72 39 42 50 8.38 3.25 0.37 1591.16 41 RWY_3_17 7.07 7.33 0.27 3028 35 12.43 6.45 0.68 864.94 29 PAU_5_33 6.97 8.13 1.16 40 47 57 7.073.19 0.32 1651.71 44 TSC_1_0 6.96 7.55 0.59 34 41 54 12.11 1.49 0.421514.78 37 CHA_1_0 6.84 7.53 0.69 43 43 58 4.47 1.18 0.32 1732.93 43UFI_2_0 6.72 7.65 0.94 35 42 49 7.86 2.25 0.42 1619.58 39 LTA_1_0 6.527.42 0.91 38 41 48 7.60 1.49 0.38 1592.05 40 AFX_3_0 6.46 7.57 1.11 4344 53 6.07 2.24 0.36 1602.31 43 AFT_3_0 6.42 7.73 1.31 39 46 56 5.673.67 0.36 1602.83 43 SFF_2_0 5.86 7.50 1.63 45 48 54 5.67 3.17 0.331800.62 46 STF_5_0 5.72 6.84 1.11 41 44 53 6.13 3.05 0.34 1700.80 43MWW_3_0 5.62 7.32 1.70 38 47 60 7.52 2.80 0.36 1678.46 42 VFI_2_0 5.345.68 0.34 32 35 45 9.70 8.26 0.40 1546.46 33 CAS_2_0 3.37 4.23 0.85 4357 67 3.86 1.96 0.14 2055.60 50

Example 1J—PSA3

Conditions:

Adsorption: 300K, 0.066 bar

Desorption: 300K, 0.0026 bar

The results are shown in Table 20

TABLE 20 PSA3 Results ΔN N^(ads) N^(des) LCD PLD mmol/ mmol/ mmol/Q_(st) ^(ads) Q_(st) ^(des) Q_(st) ⁰ (Di) (Df) Accessible density Q_(st)^(ave) Zeolite cc cc cc kJ/mol kJ/mol kJ/mol Å Å volume- kg/m³ kJ/molFAU_1_0 4.53 7.10 2.57 45 48 52 7.60 3.01 0.41 1510.18 47 KFI_1_0 4.486.21 1.73 49 50 52 6.98 1.22 0.34 1723.96 49 EMT_1_0 4.29 6.99 2.71 4549 54 8.74 3.05 0.41 1509.89 47 CHA_1_0 4.26 5.54 1.28 47 47 58 4.471.18 0.32 1732.93 47 IRY_2_0 4.21 5.31 1.10 39 46 48 11.00 6.80 0.581250.14 42 IRR_2_0 4.11 5.41 1.31 41 47 50 11.01 8.86 0.54 1244.85 44UFI_2_0 3.93 5.43 1.50 43 48 49 7.86 2.25 0.42 1619.58 45 LTA_1_0 3.925.44 1.51 44 49 48 7.60 1.49 0.38 1592.05 46 TSC_1_0 3.84 4.75 0.91 4347 54 12.11 1.49 0.42 1514.78 45 RHO_3_0 3.74 5.88 2.15 41 49 58 7.732.44 0.42 1513.04 45 AFX_3_0 3.67 5.48 1.81 45 48 53 6.07 2.24 0.361602.31 46 AFT_3_0 3.61 5.98 2.37 45 49 56 5.67 3.67 0.36 1602.83 47ITT_2_17 3.59 4.94 1.35 42 48 54 10.78 7.88 0.48 1383.09 45 PAU_5_333.49 5.67 2.18 44 50 57 7.07 3.19 0.32 1651.71 47 MWW_2_33 3.43 5.241.80 44 47 61 7.35 1.87 0.31 1770.73 46 SFF_2_0 3.17 5.99 2.82 48 50 545.67 3.17 0.33 1800.62 49 STF_2_0 2.87 5.44 2.57 46 49 55 5.56 3.07 0.331798.92 48 VFI_2_17 1.94 2.20 0.26 38 44 45 9.86 7.94 0.39 1566.89 41CAS_2_0 1.50 3.68 2.18 52 56 67 3.86 1.96 0.14 2055.60 54 RWY_3_17 1.341.41 0.07 34 35 35 12.43 6.45 0.68 864.94 34

Example 1K—PSA4

Conditions:

Adsorption: 233K, 0.066 bar

Desorption: 233K, 0.0026 bar

The results are shown in Table 21

TABLE 21 PSA4 Results ΔN N^(ads) N^(des) LCD PLD mmol/ mmol/ mmol/Q_(st) ^(ads) Q_(st) ^(des) Q_(st) ⁰ (Di) (Df) Accessible density Q_(st)^(ave) Zeolite cc cc cc kJ/mol kJ/mol kJ/mol Å Å volume- kg/m³ kJ/molRWY_3_17 6.99 9.50 2.50 29 36 35 12.43 6.45 0.68 864.94 32 FAU_5_0 5.778.75 2.98 34 36 43 8.97 4.63 0.43 1355.07 35 UFI_25_100 5.74 7.10 1.3631 34 35 8.76 3.41 0.43 1480.44 33 KFI_50_100 5.53 6.66 1.13 31 34 3210.74 4.06 0.41 1476.32 32 PAU_Si 5.32 6.14 0.82 33 32 30 10.55 3.820.38 1535.92 32 AFX_25_100 5.00 6.78 1.78 32 34 36 7.56 3.66 0.391504.77 33 CHA_25_100 4.93 6.19 1.26 31 34 32 7.23 3.82 0.41 1500.19 32EMT_5_67 4.92 7.55 2.64 31 35 44 8.96 6.59 0.42 1392.94 33 STF_50_1004.86 5.65 0.79 31 33 33 7.67 5.52 0.36 1623.58 32 RHO_10_100 4.83 7.883.05 32 35 56 7.98 3.82 0.42 1466.50 34 AFT_25_0 4.81 6.80 1.99 31 35 557.59 3.67 0.41 1489.49 33 IRY_5_50 4.46 7.09 2.63 29 36 44 10.09 6.330.57 1208.08 33 IRR_5_50 4.43 7.05 2.62 29 36 43 12.01 7.98 0.54 1201.0233 LTA_10_100 4.42 5.41 0.99 30 35 36 8.28 3.72 0.38 1422.00 32 VFI_1_04.25 6.84 2.58 32 37 36 9.67 8.69 0.41 1630.18 34 TSC_10_0 4.05 6.072.02 29 36 45 13.61 3.89 0.46 1323.95 33 ITT_5_100 3.71 6.14 2.43 29 3544 11.20 7.01 0.46 1345.06 32 SFF_25_67 3.62 5.08 1.45 30 35 51 7.625.49 0.35 1639.66 33 MWW_10_100 3.49 6.01 2.52 33 35 49 7.25 4.45 0.341625.99 34 CAS_Si 3.44 4.48 1.04 36 36 34 10.33 3.41 0.17 1833.03 36

The relationship between the working capacity and accessible pore volumefor the optimal composition of each topology has been investigated.Interestingly, almost linear correlations were observed for all theseprocesses. FIG. 2 shows the case for PSA1. Based on the linearrelationships, the upper bound of the working capacity for a specifiedprocess could be estimated for a zeolite material once its accessiblepore volume was determined.

It was further found that their average Qst are located in a narrowrange for each process. FIG. 3 shows the case for PSA1. The mean valuewith the standard deviation for all these optimal compositions werecalculated to be 27±3, 32±2, 30±3, and 40±4 kJ/mol for PSA1, VSA, PTSA1,and VTSA1, respectively. In contrast, their heats of adsorption at zerocoverage (Qsto) were located in a relatively larger range for eachprocess (not shown). The results mean that suitable average Qst wererequired for maximizing the working capacity of each topology in aspecified process. Too high an average Qst will lead to a large amountof residual adsorbed adsorbate at the desorption pressure, and thereforeto a reduced working capacity, whereas too low an average Qst will alsoresult in a low working capacity. As a result, for each topology therewas an optimal average Qst for obtaining the maximum working capacity.

It was found that for each zeolite topology there was an optimalcomposition (Si/Al ratio and K/(K+Na) ratio) that yields the highestworking capacity for the topology. Although for a specified process theoptimal composition is topology-dependent, the average heats ofadsorption of the optimal composition are close for differenttopologies. The highest performing materials were found to have bothlarge pore volume and the optimal average heats of adsorption.

Example 2—Validation of Simulations

CO₂ adsorption isotherms simulated with the developed CCFF force fieldwere compared with the experimental data for a range of zeolites withdifferent Si/Al ratios and cation compositions. FIG. 4 shows thecomparison for CO₂ in several pure K- and mixed cation zeolites. Thecalculated results come from our first-principles derived force fields;these calculations were not fitted to experimental data in any way. ForK-CHA (Si/Al=12, FIGS. 4 a and 4 b ), the simulated isotherms based onCCFF are in excellent agreement with the experimental data from Pham etal. at all three temperatures. For K-MCM-22 (Si/Al=15, FIGS. 4 c and 4 d), CCFF makes predictions that are in reasonable agreement withexperimental data reported by Zukal et al. at room and hightemperatures, but slightly underestimates the CO₂ loading at lowpressures and overestimates at high pressures at 273 K. FIG. 4 e showsthe comparison for CO₂ adsorption in KX and KY. Both materials have thesame topology, FAU, but with different Si/Al ratios, 1.23 for KX and2.37 for KY. The experimental samples prepared by Walton et al. have thecompositions K76Na10Al86Si106O384 and K5Na52Al57Si135O384 for KX (88.7%K) and KY (91.7% K), respectively (Walton, K. S.; Abney, M. B.; LeVan,M. D. Micropor Mesopor Mat 2006, 91, 78). Reasonable agreement was foundbetween the simulated isotherms and the experiments for these twosamples, although CCFF may overestimate CO₂ loading slightly at lowpressures for KX. The higher adsorption capacity of KX compared to KY inthe medium pressure region may be due to the higher concentration ofcation sites in KX, especially dual cation sites, where one CO₂ moleculecan effectively interact with two cations.

Finally, the force fields were applied to K/Na-LTA (Si/Al=1). Previousstudies on separation of CO₂/N₂ using K/Na-LTA showed that K cationsmake it difficult for CO₂ to diffuse in the zeolite because they block8MR windows. GCMC simulations alone cannot account for the blockageeffect. Data was chosen from a sample with compositionK17Na79Al96Si96O384 (17.4% K), since the blockage effect is likely to besmall for this composition (Liu, Q. L.; Mace, A.; Bacsik, Z.; Sun, J.L.; Laaksonen, A.; Hedin, N. Chem Commun 2010, 46, 4502). As shown inFIG. 4 f , the simulated isotherms at 29 8K and 343 K agree well withthe experimental data reported by Liu et al. (Liu, Q. L.; Mace, A.;Bacsik, Z.; Sun, J. L.; Laaksonen, A.; Hedin, N. Chem Commun 2010, 46,4502), but overestimated at 253 K for the whole pressure region. Thesignificant deviation may be due to the slow adsorption kinetics of CO₂in experimental measurement at this low temperature (Cheung, O.; Bacsik,Z.; Liu, Q. L.; Mace, A.; Hedin, N. Appl Energ 2013, 112, 1326).

The good performance of the CCFF force fields for CO₂ adsorption in thediverse zeolite samples represented in FIG. 4 indicates that thisapproach accurately describes these materials. This outcome means thatfor the first time a reliable force field for CO₂ adsorption in Na- andK-containing zeolites for the full range of Si/Al ratios is available.This situation opens the possibility of applying these methods toscreening of zeolite materials for CO₂ capture at different processconditions.

CO₂ adsorption isotherms were determined for the following zeolites inorder to validate the simulations. High-resolution adsorption isothermsof carbon dioxide were obtained by employing three different adsorptioninstruments. For measurements below 1 atm Autosorb-1 volumetricinstrument (Quantachrome Instr.) and in-house Cahn gravimetricmicrobalance were used. For high-pressure measurements volumetricinstrument iSORB (Quantachrome Instr.) was used. Prior to eachadsorption experiment, zeolite samples were subjected to in-situoutgassing at 400 C under vacuum of the order of 1×10⁻⁴ torr. Theexperimental isotherms were converted from excess to absolute adsorptionusing the theoretical (helium) pore volumes according to (Neimark, A.V.; Ravikovitch, P. I. Langmuir, 1997, 13, 5148)N _(abs) =N _(ex) +ρV _(p)

SSZ-35 (STF Framework Structure)

A gel of composition: 10.2 SDAOH:2.65 Na₂O:Al₂O₃:124 SiO₂:1714 H₂O wasprepared by mixing 18.2 g of deionzed water, 7.5 g of Cab-O-Sil fumedsilica, 13.8 g of 13.65% 6,10-dimethyl-5-azoniaspiro(4,5)decanehydroxide, 0.4 g 50% sodium hydroxide, 0.2 g Al(OH)₃ (53% Al₂O₃), and 20mg of SSZ-35 seeds in a plastic beaker with a spatula. The mixture wasthoroughly homogenized in a 125 ml blender for 20 minutes and thenplaced in a 45 ml teflon-lined autoclave. The autoclave was placed in170° C. oven and tumbled at 43 rpm for 7 days. The product was vacuumfiltered, washed with de-ionized water and dried in an air oven at 110°C. Phase analysis by powder X-ray diffraction showed the sample to bepure SSZ-35 zeolite. The sample was then calcined in air for three hoursat 600° C. to remove the organic template.

The sample was then ammonium exchanged by mixing 6.3 g of the calcinedsample with 6.3 g NH₄Cl in 63 mls de-ionized water for 1 hr at 60-80° C.on a hot plate stirrer. The sample was then calcined again at 600° C.for three hours in air, and then re-exchanged a second time as before.Elemental analysis by ICP gave Si/Al=78 and Na/Al=0.04.

The CO₂ adsorption isotherm for SSZ-35 is shown in FIG. 5 , which showsthe comparison to the simulations (open squares) and the experimentalSSZ-35 (points).

SSZ-13 (CHA Framework Structure)

A gel of composition: 3 SDAOH: 10 Na₂O:Al₂O₃: 35 SiO₂: 1000 H₂O wasprepared by adding 8.9 g of 25% trimethyladamantaammonium hydroxide, 0.7g of 50% NaOH, 21.0 g of sodium silicate (29% SiO₂, 9% Na₂O), 42.3 g ofde-ionized water and 2.1 g of USY zeolite (Englehard EZ-190, 60.2% SiO₂,17.2% Al₂O₃) to a 125 ml teflon autoclave. The mixture was reacted forthree days at 140° C. in a tumbling oven rotating at 20 rpm. The productwas vacuum filtered, washed with de-ionized water and dried in an airoven at 115° C. Phase analysis by powder X-ray diffraction showed thesample to be pure SSZ-13 zeolite. Elemental analysis by ICP gaveSi/Al=8.2 and Na/Al=0.49.

Zeolite RHO

A gel of composition: 0.44 Cs₂O: 0.5 TEA₂O: 2.46 Na₂O:Al₂O₃: 11.1 SiO₂:110 H₂O was prepared by first preparing a cesium, sodium aluminatesolution by dissolving 7.9 g NaOH in 10 mls distilled H₂O and 10.4 g 50%CsOH. Added 6.16 g of Al₂O₃.3H₂O and heated to a boil until aluminadissolved and then cooled down to room temperature. To a 250 ml beakeradded 65.8 g of 40% colloidal silica (Ludox HS-40), 14.5 g of 40% TEAOH,cesium, sodium aluminate solution and enough water to bring the totalweight of solution to 125 g. The solution was mixed thoroughly with aspatula, transferred to a 125 ml teflon bottle and allow to age at roomtemperature for four days and then in an 85° C. oven for three days. Theproduct was vacuum filtered, washed with distilled water and dried in anair oven at 115° C. Phase analysis by powder X-ray diffraction showedthe sample to be pure RHO zeolite. Elemental analysis by ICP and AA gaveSi/Al=3.1, Cs/Al=0.45, and Na/Al=0.51.

In another example SSZ-13 material has been prepared with Si/Al=7, andNa/Al=0.75. CO₂ adsorption isothermss for SSZ-13 (open symbols) atdifferent temperatures are compared to the simulated CO₂ adsorptionisotherms (solid symbols) in FIG. 6 .

SSZ-16 (AFX Framework Structure)

A gel of composition: 0.3 SDA(OH)2: 0.3 NaOH: 0.025 Al₂O₃:SiO₂: 30 H₂Owas prepared by adding 15.7 g Ludox LS-30 colloidal silica, 31.6 g of22.6% Pentane-1,5-bis(N-methylpiperidinium hydroxide), 1.5 g of 50%NaOH, 0.8 g USALCO 45 sodium aluminate solution (19.3% Na2O, 25% Al₂O₃),and 5.4 g deionized water to a plastic beaker. The mixture was stirredfor three hours and then placed in two 23 and one 45 ml teflonautoclaves. It was then reacted for three days at 160° C. in a tumblingoven rotating at 20 rpm. The product was vacuum filtered, washed withde-ionized water and dried in an air oven at 115° C. Phase analysis bypowder X-ray diffraction showed the sample to be pure SSZ-16 zeolite.Elemental analysis by ICP gave Si/Al=4.7 and Na/Al=0.59.

CO₂ adsorption isotherms for SSZ-16 (points) are compared to thesimulated CO₂ adsorption (lines) in FIG. 7 .

What is claimed is:
 1. A vacuum temperature swing adsorption process forseparating a CO₂ from a feed gas mixture, wherein the process comprises:a) subjecting the feed gas mixture comprising CO₂ to an adsorption stepby introducing the feed gas mixture into a feed input end of anadsorbent bed, wherein the adsorbent bed comprises: a feed input end anda product output end; and an adsorbent material selective for adsorbingCO₂, wherein the adsorbent material comprises one or more of thefollowing: (i) a zeolite having a Si/Al ratio above about 100 with a CASframework structure; or (ii) a zeolite with a framework structureselected from the group consisting of AFT, AFX, CAS, DAC, EMT, EUO, HEU,IMF, IRR, IRY, ITH, ITT, KFI, LAU, MFS, MRE, MTT, MWW, NES, PAU, RRO,RWY, SFF, STF, STI, SZR, TER, TON, TSC, TUN, VFI, and a combinationthereof, having: a. a Si/A ratio of about 1 to about 100; and b. apotassium cation concentration of 0% to 100%; wherein the adsorbent bedis operated at a first pressure and at a first temperature, and whereinat least a portion of the CO₂ in the feed gas mixture is adsorbed by theadsorbent bed and wherein a gaseous product depleted in CO₂ exits theproduct output end of the adsorbent bed; b) stopping the introduction ofthe feed gas mixture to the adsorbent bed before breakthrough of CO₂from the product output end of the adsorbent bed; and c) simultaneouslyheating the adsorbent bed to a second temperature higher than the firsttemperature and passing a purge gas, substantially free of CO₂, throughthe adsorbent bed thereby resulting in a reduction in the pressure inthe adsorption bed to a second pressure, resulting in desorption of atleast a portion of CO₂ from the adsorbent bed and recovering at least aportion of CO₂.
 2. The process of claim 1, wherein the first temperatureis from about −20° C. to about 80° C. and the first pressure is suchthat the partial pressure of CO₂ is from about 0.5 bar to about 7 bar.3. The process of claim 2, wherein the first temperature is from about0° C. to about 50° C.
 4. The process of claim 1, wherein the secondtemperature is from about 50° C. to about 250° C., and the secondpressure is such that the partial pressure of CO₂ is from about 0.05 barto about 0.5 bar.
 5. The process of claim 1, wherein the secondtemperature is from about 75° C. to about 125° C., and the secondpressure is such that the partial pressure of CO₂ is from about 0.08 barto about 0.3 bar.
 6. The process of claim 1, wherein the secondtemperature is from about 175° C. to about 225° C., and the secondpressure is such that the partial pressure of CO₂ is from about 0.09 barto about 0.4 bar.
 7. The process of claim 1, wherein the feed gasmixture is a natural gas stream.
 8. The process of claim 1, wherein theadsorbent material has a working capacity of about 3.0 mmol/cc to about14.0 mmol/cc.
 9. The process of claim 1, wherein the adsorbent bed hasopen flow channels throughout its entire length through which the feedgas mixture is passed.
 10. The process of claim 1, wherein the adsorbentbed is a parallel channel contactor.
 11. The process of claim 1, whereinthe adsorbent material is a zeolite with a framework structure selectedfrom the group consisting of AFT, AFX, CAS, DAC, EMT, EUO, HEU, IMF,IRR, IRY, ITH, ITT, KFI, LAU, MFS, MRE, MTT, MWW, NES, PAU, RRO, RWY,SFF, STF, STI, SZR, TER, TON, TSC, TUN, VFI, and a combination thereof,having: a. a Si/Al ratio of about 1 to about 75; and b. a potassiumcation concentration of 0% to about 90%.
 12. The process of claim 1,wherein the adsorbent material comprises a zeolite with a frameworkstructure selected from the group consisting of AFX, AFT, KFI, PAU, TSC,and a combination thereof, having: a. a Si/Al ratio of about 1 to about20; and b. a potassium cation concentration of 0% to about 40%.
 13. Avacuum temperature swing adsorption process for separating a CO₂ from afeed gas mixture, wherein the process comprises: a) subjecting the feedgas mixture comprising CO₂ to an adsorption step by introducing the feedgas mixture into a feed input end of an adsorbent bed, wherein theadsorbent bed comprises: a feed input end and a product output end; andan adsorbent material selective for adsorbing CO₂, wherein the adsorbentmaterial comprises one or more of the following: (i) a zeolite with aframework structure selected from the group consisting of CHA, FAU, FER,MFI, RHO, UFI and a combination thereof, having: a. a Si/Al ratio ofabout 1 to about 20; and b. a potassium cation concentration of 0% toabout 40%; or (ii) a zeolite with a LTA framework structure having: a. aSi/Al ratio of about 1 to about 20; and b. a potassium cationconcentration of about 5% to about 40%; wherein the adsorbent bed isoperated at a first pressure and at a first temperature, and wherein atleast a portion of the CO₂ in the feed gas mixture is adsorbed by theadsorbent bed and wherein a gaseous product depleted in CO₂ exits theproduct output end of the adsorbent bed; b) stopping the introduction ofthe feed gas mixture to the adsorbent bed before breakthrough of CO₂from the product output end of the adsorbent bed; and c) simultaneouslyheating the adsorbent bed to a second temperature higher than the firsttemperature and passing a purge gas, substantially free of CO₂, throughthe adsorbent bed thereby resulting in a reduction in the pressure inthe adsorption bed to a second pressure, resulting in desorption of atleast a portion of CO₂ from the adsorbent bed and recovering at least aportion of CO₂.